Automatic Vs Manual exhaust system

**WillB6A4** · 08-13-2014 07:45 AM

I want to buy a new catback and a guy has one off his automatic B6, i have a manual B6, is it interchangeable? Its a milltek catback by the way. Thanks

**drjonez** · 08-13-2014 07:46 AM

The downpipe is different between the two, solve that problem and you should be fine.

**WillB6A4** · 08-13-2014 07:56 AM

Can i just buy a different downpipe or do i have to make something

**evo_ski** · 08-13-2014 08:03 AM

Buy the Techtonics Tuning downpipe. That is what I just installed last weekend. Great quality and pretty decent price. It is around $280 shipped from their website with gaskets.

**WillB6A4** · 08-13-2014 08:17 AM

I have a test pipe, it will bolt right up?

**ZipMeUpJ** · 08-13-2014 08:35 AM

yes, as long as you buy their downpipe that doesnt include the cat section

**evo_ski** · 08-13-2014 08:37 AM

It will bolt up to any factory fit test pipe, cat, or high flow cat. So yes.

**widgget** · 08-13-2014 08:42 AM

TTTuning downpipe worked fine for awhile, the flex joint rusted out after two years and i needed to weld a new one in. other then that i'm still running it until the v6 swap.

allot of exhaust systems for the automatic don't come with a downpipe like the manual version does (you just have to source your own or use the original one), which is why the automatic systems are normally a hundred or two cheaper then the manual counterparts.

**WillB6A4** · 08-13-2014 09:01 AM

How can i use the original. Will it fit the same?

**ZipMeUpJ** · 08-13-2014 09:04 AM

your original downpipe is not the same diameter as the milltek. Depending on how the PO mated his exhaust to whatever DP he was using will decide what route you have to take to mate the exhaust to your stock DP. aka just take it to an exhaust shop they will know what to do

**WillB6A4** · 08-13-2014 09:05 AM

The reason i wanted a used one was so i didnt have to spend so much money would it be cheaper just for an exhaust shop to do it rather than buy a new down pie

**WillB6A4** · 08-13-2014 09:06 AM

Pipe

**evo_ski** · 08-13-2014 09:22 AM

Honestly I doubt an exhaust shop would make a piece that fit as well as the Techtonics one that is mandrel bent for the same kind of price. It is EXTREMELY tight quarters in there trying to fit the pipe through, so it would be very hard for them to accurately fit something unless they are a super skilled shop.

Looks like the Milltek is a 2.5" system so if you order the Full 2.5" version of the Techtonics pipe it should mate right up with a clamp. I would verify with the seller that the Milltek doesn't have any sort of reducer to mate it up to the factory downpipe before you pick something up.

**WillB6A4** · 08-13-2014 09:24 AM

What do you mean by a reducer?

**Charles.waite** · 08-13-2014 09:26 AM

As a point of clarification, the most exhausts for the b6 are labeled as catback, but thats technically wrong. They are almost always downpipe-back. Hence when we say you need to sort out the downpipe part, we really mean you need to sort out the downpipe part. Unless you think the exhaust gasses are magically going to flow from the catalyst exit, nearly 3' to the start of the center muffler piping...

**evo_ski** · 08-13-2014 09:28 AM

A reducer simply means that the piping is 2.5" but then has a transition to a smaller size at the end so that it can fit on our factory 2" downpipe. You need to find out if the mating end of the exhaust is factory sized or 2.5".

The pipe at the top of this picture has a reducer on the left side to make the 2.5" pipe fit the factory downpipe. Since a reducer will decrease flow in that section I had a shop cut off the reducer and weld on a section of 2.5" pipe so that my exhaust would be 2.5" from the catalytic converter all the way to my resonators rather than having a useless reducer in the middle for no reason.

**WillB6A4** · 08-13-2014 09:31 AM

He said its 2.25in at the y pipe and 2in everywhere else

**evo_ski** · 08-13-2014 09:33 AM

Ask him if he has it connected to his stock downpipe or if it is an aftermarket one.

**WillB6A4** · 08-13-2014 09:35 AM

He said stock

**WillB6A4** · 08-13-2014 09:36 AM

**evo_ski** · 08-13-2014 09:45 AM

Okay, then unless you really want one you don't need an aftermarket downpipe, you can just bolt that exhaust right up to what you have. That is the non resonated version of the exhaust so it will be louder than the ones with resonators, FYI.

**WillB6A4** · 08-13-2014 09:46 AM

Even though its an automatic system it will go,on a manual

**evo_ski** · 08-13-2014 09:48 AM

Correct.

**customa4** · 08-13-2014 09:50 AM

Your car is a quattro, right?

**WillB6A4** · 08-13-2014 10:03 AM

Yes

**customa4** · 08-13-2014 10:09 AM

Alright just making sure. The exhaust systems to differ between quattro and FWD as well.

**evo_ski** · 08-13-2014 10:10 AM

The more I look at that exhaust it looks like that might be a FWD exhaust which will not fit. Verify with the seller that they have quattro.

**WillB6A4** · 08-13-2014 10:10 AM

He just told me its off a quattro.

**evo_ski** · 08-13-2014 10:19 AM

Sounds like you are golden then.

**WillB6A4** · 08-13-2014 10:20 AM

Thanks for all the help

**WillB6A4** · 08-14-2014 03:39 PM

Still very hesitant about purchasing this. He said it was on an automatic is it gauranteed to fit on my manual

**WillB6A4** · 08-14-2014 03:54 PM

Hes saying its got the stock downpipe that came with the car

**Charles.waite** · 08-14-2014 04:01 PM

Recap: You have a manual (5speed?). This exhaust is from an automatic. The downpipe will be useless for you, however the rest of the exaust (from the downpipe back) will absolutely fit. The downpipe is the only part that differs between 5-speed, 6-speed, and Tiprtonic Exhausts on the b6.

**WillB6A4** · 08-14-2014 04:04 PM

So i can just put my original downpipe on thisexhaust and it will be good?

**evo_ski** · 08-14-2014 04:10 PM

The downpipe that is bolted to your car will attach as normal to this exhaust. You do not need nor would you want his downpipe since his won't quite fit your car. Everything from a manual and auto car is exactly the same except for the downpipe.

Case in point, I purchased a Magnaflow 16601 system and have an automatic. A friend has the exact same exhaust, but his is mounted to a manual.

**WillB6A4** · 08-14-2014 04:31 PM

Im just making sure, i dont wanna drop alot of money and not have it work and have to spend more.

**docurley** · 08-14-2014 11:11 PM

Well I took a look at Milltek website and they do not list the triptronic gearbox in Quattro as an option so based on that it maybe just a stock system with a alterd downpipe.

http://m.millteksport.com/products.bymake.cfm?makeid=1

Milltek systems are made with downpipes and from what I know the b6/b7 6 speed at almost the same bar downpipes and the B7 tailpipes are longer (I know because I had a b7 on my car).

B6 5 speed box down is different again from the 6 speed and fwd system is totally different.

conclusion is (not unless Milltek have a different website for the USA) is his system for a 5 or 6 speed and how is his down pipe modified or is he giving you the adapter for the downpipe and will it fit.

The downpipe for my system did not fit so my mate modified the downpipe to mate the milltek till I bought a new one for the b6. So the down will need to be modified.

**diagnosticator** · 08-15-2014 12:41 AM

You can use your original down pipe. However, without a larger 2.5 diameter matching down pipe that will fit the Milltec 2.5" mid pipe without a pipe size adapter to join the 2" stock down pipe to the 2.5" Milltec mid pipe, that is, with the 2" stock down pipe>2.5" mid pipe, there will not be much benefit because of the smaller stock down pipe, the pressure drop through the turbo turbine will not be increased, since the down pipe size effects the back pressure at the turbine exit a lot more than the exhaust mid pipe diameter after the down pipe. Increased pressure differential across the turbine will only result with a larger cat and down pipe. On a turbocharged engine, the largest turbine inlet to turbine outlet pressure differentail is where increased performance is realized. Even if a "test" pipe is used, the benefits of a performance exhaust system connected to a stock down pipe, will not be effective. A HFC and a 2.5" down connected to a stock system mid pipe > tail pipes is more effective compared to the reverse arrangement you would have.