Full APR exhaust-Power Gains vs. Headers

[IronMike]

I am debating putting full APR exhaust on the S4 and was wondering if the claimed 25hp/35lb torque on APR's website is even close to accurate. That seems like a good gain to improve 0-60mph times and that is what I am looking for. For those that have this setup, or just the cats, please let me know what you think of the performance gains if any. Also, what is the install cost for this as well, (full exhaust is about 2,000 on sale).

I am also debating the headers, but after the install and parts with cats, it seems to be well over $5,000. Not sure if the additional gains would be worth the cost difference.

Finally, I am not so sure if the headers with cat-back would be waaay to loud for me (and the wife since she will drive it occasionally), and drone???

Opinions welcome. THANKS IN ADVANCE.

[jfunkey]

Bro the APR Dp's are small the smallest DIA I think of all the Dp's other then stock

To tell you the truth. Go piggies and FI or APR cat back. Your in Mi. so you can go catless piggies.

There is going to be a big diference between headers and Dp's but its about 20ft-lbs of TQ to the wheels. That is a big difference. But you need to look at what you future plans are for the car and then make the choise from there.

PLuss your close the VAST Performance. Ive checked them out and they make the piggies and I think they are a APR dealer.

Save the money on the Dp's and get the piggies.

Headers are great but they are not for everyone. I ordered a set and will let you know if they are worth all the money cause Im going to do piggies a week before I do the headers to see the difference. SO Ill keep you posted

[dextrek]

I have a full APR set up on my car currently. Since you are in Michigan, we can meet up and you can hear it in person as well as feel the gains.

Were you at the MotorStadt this year? We did some sound testing between the S4's and my vote went to a Catless DP w/ custom catback with Magnaflows as it was the loudest. But that's just me. My APR is pretty nice, but nothing crazy since it has resonators. It has a nice tone to it, especially in 3rd gear. Also many people agree that the quad tip is quite aggresive since it's 3 inch tips on all four.

Let me know if you want to arrange something.

[SuperAvant]

Actually the biggest gains I have seen so far from Downpipes have come from the APR DP's. The APR DP's have 200 mil cats which I think are the highest flowing ones out there. Remember, bigger isnt always better for flow.

[rxbike]

Bro the APR Dp's are small the smallest DIA I think of all the Dp's other then stock

To tell you the truth. Go piggies and FI or APR cat back. Your in Mi. so you can go catless piggies.

There is going to be a big diference between headers and Dp's but its about 20ft-lbs of TQ to the wheels. That is a big difference. But you need to look at what you future plans are for the car and then make the choise from there.

PLuss your close the VAST Performance. Ive checked them out and they make the piggies and I think they are a APR dealer.

Save the money on the Dp's and get the piggies.

Headers are great but they are not for everyone. I ordered a set and will let you know if they are worth all the money cause Im going to do piggies a week before I do the headers to see the difference. SO Ill keep you posted

Not sure how my APR 2.5" DP is smaller than piggies (JHM/FI) 2.5". Must be a CA metal walls and AZ metal wall thickness since all APR exhaust are built by Billy Boat Exhast anyways...
Enough said, I just had my APR DP installed to my 3 month old APR exhaust.
Top RPM end power is there but I think at a slight loss in lower RPM BUTT response. Noise wise after a few days is not as bad as when I first got it. (I have the high flow cat ).With the windows down, you are approaching the sounds of american muscle sound, though not as loud by any means. Windows up which is how I drive most of the time, it was only a slight noise increase. You should take up the other member's offer to hear the system. i need to get some time to record a sound clip and post it vs. the 65 mustang with a 351 cu in and flow master exhaust.

[dextrek]

Actually the biggest gains I have seen so far from Downpipes have come from the APR DP's. The APR DP's have 200 mil cats which I think are the highest flowing ones out there. Remember, bigger isnt always better for flow.

Isn't Fast Intention also 200 mil as well? or are they 250 mil?

[dextrek]

Not sure how my APR 2.5" DP is smaller than piggies (JHM/FI) 2.5". Must be a CA metal walls and AZ metal wall thickness since all APR exhaust are built by Billy Boat Exhast anyways...
Enough said, I just had my APR DP installed to my 3 month old APR exhaust.
Top RPM end power is there but I think at a slight loss in lower RPM BUTT response. Noise wise after a few days is not as bad as when I first got it. (I have the high flow cat ).With the windows down, you are approaching the sounds of american muscle sound, though not as loud by any means. Windows up which is how I drive most of the time, it was only a slight noise increase. You should take up the other member's offer to hear the system. i need to get some time to record a sound clip and post it vs. the 65 mustang with a 351 cu in and flow master exhaust.

Well said...

But I don't think piggies are 2.5". I think they are stock piping size which is 2.15", but JHM/FI downpipes are 2.5".

[B6guy42]

APR's are 200Cell cats? I thought Milltek was the only company that offered 200Cell cats. I stand corrected I guess.

[tadhgbrosnan]

I am debating putting full APR exhaust on the S4 and was wondering if the claimed 25hp/35lb torque on APR's website is even close to accurate. That seems like a good gain to improve 0-60mph times and that is what I am looking for. For those that have this setup, or just the cats, please let me know what you think of the performance gains if any. Also, what is the install cost for this as well, (full exhaust is about 2,000 on sale).

I am also debating the headers, but after the install and parts with cats, it seems to be well over $5,000. Not sure if the additional gains would be worth the cost difference.

Finally, I am not so sure if the headers with cat-back would be waaay to loud for me (and the wife since she will drive it occasionally), and drone???

Opinions welcome. THANKS IN ADVANCE.

Do not buy DPs with the idea that it will make your car faster. The reality is that for $3k or so installed, a fullback exhaust is very likely to leave you disappointed. It will sound amazing but it ain't going to be noticeably faster.

Personally, I think the fullback is worth the price b/c of the sound alone. It sounds that good. If you can afford it and you want to make the V8 sing, then do it. Just don't expect to knock a half second off your acceleration runs.

[somethingcorp]

all in all are you fellas basically saying in this order that... header have the most significant hp\tq gains then would come peggie pipes followed by downpipes??

then tadhgbrosnan is basically saying that if i bought a exhaust i would see any improvement in power-gains.. is that just with the exhaust or is that both peggies all the way??

much like ironmike i am in the market for an exhaust but i am not really following were you guys are going with the difference between headers\piggies\downpipes and would like to find the best product that generates the most power.. headers are outta the question both cost and practicality on a daily driver doesn't sound like it fits me well

[Justincredible]

Not sure how my APR 2.5" DP is smaller than piggies (JHM/FI) 2.5". Must be a CA metal walls and AZ metal wall thickness since all APR exhaust are built by Billy Boat Exhast anyways...
Enough said, I just had my APR DP installed to my 3 month old APR exhaust.
Top RPM end power is there but I think at a slight loss in lower RPM BUTT response. Noise wise after a few days is not as bad as when I first got it. (I have the high flow cat ).With the windows down, you are approaching the sounds of american muscle sound, though not as loud by any means. Windows up which is how I drive most of the time, it was only a slight noise increase. You should take up the other member's offer to hear the system. i need to get some time to record a sound clip and post it vs. the 65 mustang with a 351 cu in and flow master exhaust.

2nd APR dp are good. The issue with Dp's are just the cat placement. You need to move the pre cat back further. The fact that ALL the after market Audi and only Audi aftermarket Dp's have the pre cats still is the issue that puts the Piggies up on the HP chart over the typical Dp's.

Having the cat that close to the motor is not as good has retaining your main stock cat in your Stock Dp's but removing the pre cat.

I did a write up and to just kinda skim threw it. aftermarket Dp's all help but how they help is the issue. The results with aftermarket dp's is less restriction but still a restriction too close to the motor. This is why all the other performance company's for all the other cars domestic and other wise that have PRE cats as well REMOVE the PRE cat and re place the MAIN cat in there design.

Any way you put in aftermarket Dp's you will still have the Pre cat and you will get a good boost in flow out of the exhaust. BUT take you stock Dp's and just remove the PRE cat (you will need to move one of your 02's cause you will get a cel thus this is why people send them in to get modded)
So you take you stock Dp's and just remove the PRE cat change noting else and you will get the same if not better flow but you will also get lower Exhaust temps, more ignition timing, faster A/F readings and more stable transition threw the rev range

So if your looking for the scale of power

headers
ALL after market Dp's with out cats (these are here cause of the dia and bends)
Piggies with out cats
piggies
aftermarket Dp's

A little more info http://www.audizine.com/forum/showthread.php?t=250634

[beemercer]

So if your looking for the scale of power

headers
ALL after market Dp's with out cats (these are here cause of the dia and bends)
Piggies with out cats
piggies
aftermarket Dp's

Agreed, it kinda goes like Headers>>>Catless DP's>Catless Piggies>Piggies>Dp's.

The headers are going to be significantly better than any other options because of the long tube tuned design will enhance and bolster low-end torque (based on dyno charts posted by 10mpg the torque will come on strong at roughly 1000rpm earlier), as well as providing the largest effective pipe cross sectional area (a weighted average between the log manifold and downpipe), which allows for an increased maximum flow level. This increased maximum flow is where the high-rpm power will be gained (again this was supported by the dyno charts posted), since the engine will be able to breathe better (specifically exhale in this analogy). This ability to clear exhaust gases more efficiently is important because it forms the foundation for more involved engine modification involving the intake process of the motor (Intake manifold, cams, head work, forced induction) since due to conservation of mass you can't put more air into the motor than you can clear out.

Catless DP's are going to be better than fully catless piggies due to a decrease in major and minor losses incurred by the pipe diameter and excessive bends in the stock downpipes respectively.

As Justin elaborated main-cat piggies will perform better than pre-cat downpipes because of the extreme restriction created by the pre-cat. This restriction is not limited to just the gas flow, it also traps heat between the pre-cat and the combustion chambers (which are easily within 2ft of each other). Since the heat gets trapped so close to the combustion chambers it logically follows that the temperature within the combustion chamber increases, causing the motor to retard timing to avoid self-ignition. The retarded timing, combined with gas flow restriction is the reason why the pre-cat present in both the unmodified stock downpipes and catted aftermarket downpipes are such performance robbers.

[IronMike]

I appreciate all the help. I just checked VAST performance's website and their piggies are $405 (not including installation). For that price, DP's and headers seem to be waaay too much money for not that much more power. So the best setup is for CATLESS piggies which would be the $405 and not have to buy a catback system (APR catback for example)/use the OEM cats??? Or am I way off? I have no clue when it comes to this. Also, will catless piggies cause terrible drone and loudness that will make my wife want to kill me?

To be honest I would go with the headers if it were less than $3,000, but I think it will be loud as all hell (pissing my wife off), am I right? What is your prediction on the install cost of the headers and where would I go in michigan to have it done???

Thanks a lot and sorry for all the questions, just don't want to blow money on something I will regret.

[dextrek]

I appreciate all the help. I just checked VAST performance's website and their piggies are $405 (not including installation). For that price, DP's and headers seem to be waaay too much money for not that much more power. So the best setup is for CATLESS piggies which would be the $405 and not have to buy a catback system (APR catback for example)/use the OEM cats??? Or am I way off? I have no clue when it comes to this. Also, will catless piggies cause terrible drone and loudness that will make my wife want to kill me?

To be honest I would go with the headers if it were less than $3,000, but I think it will be loud as all hell (pissing my wife off), am I right? What is your prediction on the install cost of the headers and where would I go in michigan to have it done???

Thanks a lot and sorry for all the questions, just don't want to blow money on something I will regret.

Where in Michigan are you located? There are few shops that will be able to do the header work near Detroit area, but I don't know about nothern or western Michigan.

[jfunkey]

Bro in the end Piggie cat less for the win.

If your chasing the hp tq to the best its got then you are looking for the headers. I ordered the headers cause on a N/A car you are chasing any hp tq gain you can get and the bump the give is what Im looking for. There are no other mods other then a S/C that are going to bump the tq and its not like you can get Tq from anyother parts that are going to give you that result. Other then NOS S/C etc etc.

the cost to hp tq gain is going to go up more and more when you reach a point. So the extra money spent for the 20+ ft lbs of tq to the wheels for me is money well spend. Because of people like sway,justin,and some of the others that have pulled there motors Im going to tackle this one my self. So the 2500$ installed is a good price for me.

I will how ever be doing the cat less piggies about 1 week before I do the motor pull for the headers and I will give my feed back.

[ZEUSROTTY]

My car has APR downpipes, an x-pipe, 2 off brand straight through bullets, and flowmaster D40's and its got the best sound I have ever heard from an S4... So save yourself some money, and just get the APR downpipes, take them to a custom exhaust shop that is reputable, and get a custom job done... you could actually skip the cross pipe if you wanted... It definetly has more power now though... maybe tomorrow I will go get some sound clips made...

[IronMike]

Where in Michigan are you located? There are few shops that will be able to do the header work near Detroit area, but I don't know about nothern or western Michigan.

I am from the Detroit area (White Lake), if the labor cost is less than $1,000 I would probably go for it.

Also, if the headers add 37lb torque to the wheels than that is around 50b torque compared the the APR claimed 35lbs for full exhaust (not at the wheels). APR MUST be overestimating their #'s if that is the case.

[IronMike]

bump. If I go with the piggies, should I go with AWE (2.25) or Fast Intentions (2.5 diam)??? Not sure if the diameter will matter, but Vast recommends AWE (maybe their partners?). What are your opinions? On this and prior post.

[Justincredible]

Going with what ever Dp's you choose the next most important thing is the cat back ZEUSROTTY said it best flowmaster 40's are sick but they can be a little over the top depending on what your doing. I have a clip Ive posted some where but if you want to hear it let me know I can post the link.


Here is the thing. AWE always has good stuff. You know the fitment is going to be spot on and the Finnish is always top notch but if the AWE is 2.2 you have to pass for sure. Ive always been a fan of FI danny is a great guy and makes a great piece sounds good and always fits nice.

If your going cat less you are going to want a res system and a X pipe. you can take the res out of you want later. If your looking to go custom that's fine. P.M. me I can put you in touch with a great exhaust guy in Mi.

Either way you go you are going to want to make sure its 2.5 All the way threw with no point less then that

[ZEUSROTTY]

Going with what ever Dp's you choose the next most important thing is the cat back ZEUSROTTY said it best flowmaster 40's are sick but they can be a little over the top depending on what your doing. I have a clip Ive posted some where but if you want to hear it let me know I can post the link.


Here is the thing. AWE always has good stuff. You know the fitment is going to be spot on and the Finnish is always top notch but if the AWE is 2.2 you have to pass for sure. Ive always been a fan of FI danny is a great guy and makes a great piece sounds good and always fits nice.

If your going cat less you are going to want a res system and a X pipe. you can take the res out of you want later. If your looking to go custom that's fine. P.M. me I can put you in touch with a great exhaust guy in Mi.

Either way you go you are going to want to make sure its 2.5 All the way threw with no point less then that

The bullets quiet it down pretty well, and there is a big power increase between running w/my setup, compared to just the d40s... This motor needs the back pressure, and dont let anyone fool u into thinking otherwise...

[Justincredible]

The bullets quiet it down pretty well, and there is a big power increase between running w/my setup, compared to just the d40s... This motor needs the back pressure, and dont let anyone fool u into thinking otherwise...

Thus my X pipe. I hear you I did ton of testing and super long conversations with flowmaster and other exhaust company's about the Dp's and cat back section. The exhaust is a System if you get all the rite pieces it works well and make great power. I followed there advice to a tea and I got SUPER results.

Im looking to beat my 13.3 @ 107 with the headers this fall tho. With a automatic Its always hard to find the power. But as you already know With the balanced exhaust and over all system it makes a difference.

[ess_four]

Is there any way of checking the amount of back pressure available? Is it measureable? How much is required?

[Justincredible]

No need to check for or measure back pressure. Its best to follow this rule.

With cats you are going to get more then needed back pressure. With out cats you can get the amount of back pressure you need with a H if you have 2.2 or a X if you have 2.5 anything bigger then 2.5 is way bigger then a 4.2L motor would need and thus just not helping

[ess_four]

So I guess my straight downpipe, 100 cell main cat, h-pipe, 2.5" bore systems provides sufficient back pressure?

Thanks

[beemercer]

No need to check for or measure back pressure. Its best to follow this rule.

With cats you are going to get more then needed back pressure. With out cats you can get the amount of back pressure you need with a H if you have 2.2 or a X if you have 2.5 anything bigger then 2.5 is way bigger then a 4.2L motor would need and thus just not helping

Sounds about right, I have a catless non-resonated milltek fullback (2.25"/H-pipe) and I didn't lose too much low down torque.

[SuperAvant]

Sounds about right, I have a catless non-resonated milltek fullback (2.25"/H-pipe) and I didn't lose too much low down torque.

I am interested in seeing how your car runs... We need to do some pulls!

[beemercer]

I am interested in seeing how your car runs... We need to do some pulls!

Definitely, I'm still not tuned at this point but we'll see how it goes. And I'll have a passenger so it the weight should be a bit more even. Friday night is gonna be quite the cruise, 2AM from Worcester to New Jersey, open roads, a bunch of hooligans in Audi's...