HJS Downpipe on stock tune?

[TToysRuS]

Curious if anyone has run an aftermarket, high flow catted downpipe on the stock tune for a TTRS without check engine lights, running issues/etc. The HJS one is a beauty and would add nicely to the overall sound.

[Jeff_Jeske]

If the catted downpipe is more high flow than OEM you will run into issues on the stock tune. It will not only affect the O2 reading but also the boost curve throughout the powerband.

If you aren't planning to tune the car then I wouldn't go changing parts as it won't really provide much benefit anyway.

[TToysRuS]

Fair, just was about the noise. Thanks man!

[Jeff_Jeske]

If you want more noise remove the secondary cats .... and if that isn't enough toss on an exhaust. Neither will do anything for power but it will be significantly louder and both are very easy to revert in the event warranty work is required.

[TToysRuS]

1st one is done and def a much better note overall. I did notice a touch more acceleration but nothing drastic, just seems more eager to go, probably spool improvements is all.

[LakeTahoeQuattr]

I think one will achieve gains from just bolts on alone and a stock tune. I plan to post a dyno after I install the DP, midpipes, IC, 4" inlet, & 4" intake. I am willing to gamble ill see atleast 30wheel and faster spool. Still while retaining my 2y warranty it has left.

I am however concerned also about putting on a HF cat and not having a cel or any other problematic issues you described because it is a stock tune. Guess well see..

[kevin#34]

downpiwpe, midpipes, inlet, intake, and still hoping to retain your warranty?

[LakeTahoeQuattr]

Yea parts could easily be removed if something catastrophic happens. Else my svc manager has no problem with the parts, were boys. Not like I let them work on the car regardless

[kevin#34]

lucky

[TToysRuS]

Yea parts could easily be removed if something catastrophic happens. Else my svc manager has no problem with the parts, were boys. Not like I let them work on the car regardless

Not everything is up to a dealership. If you damage the engine, the dealer cannot guarantee warranty fulfillment when the regional reps for Audi get involved to verify tune status/etc. You'll find that out the hard way if anything happens that has serious engine damage involved. Audi knows full well people modify these cars and wont be shelling out for a new engine or transmission/etc without doing their due diligence first. And frankly, what you're proposing is warranty fraud by removing the parts and putting it back to stock appearance/etc as if you never modified the car. Pay to play, own the mods and take the risk, or dont and enjoy your warranty.

[Jeff_Jeske]

I say just tune the car. It will probably be safer and more fun to have mods that match the tune than something that doesn't. The engine and trans are about as rock solid as you can hope for.

For the most part the off the shelf tunes have proven to be extremely safe. If you want more and yet want to be conservative just run something like the UNI Stage 2 93 tune with UNI DP. No check engine lights, able to pass emission testing and still run mid 10s.

[comingabriel]

What stops the car from adapting to an aftermarket hf downpipe?
My 2017 Golf R had just a HF 200 cell dp added on a stock tune, and there was a power increase.
It was much more noticed when I removed it (prior to trading for a 2018 RS3), but it never overboosted or had any drivability issues, just it feeling signif responsive and it was butt dyno faster.
Oh, I also had a dry aFe intake drop in filter as well.
There was a minute when it was much more modded prior to the above, (when I tried tunes, a JB4, etc), but I digress.

Why doesn’t this car adapt and enforce control to changes to like what the OP wants to do?

[Jeff_Jeske]

I'm not saying you can't throw a DP on the car with a stock tune. You certainly can but the results will be lack luster. The stock tune has plenty of nannies that will still limit the performance of the car. You will also most certainly get a code for cat efficiency.

Furthermore, of all bolt on mods, the downpipe is the biggest PITA to install and uninstall. From messing with the subframe to having to beat off (lol) the driveshaft I just don't think the juice will be worth the squeeze. The performance will still be lackluster.

Right now I'm at stage 2 E85 and if I could do it all over again I'd stick with Stage 1 E85 with only a FMIC and TCU tune.

Stage 1 E85 will give you 90% of the available power with the stock turbo. Stage 1 E85 is more power than Stage 2 93 octane and you don't need an intake, inlet, injectors, downpipe or even another investment into a next level tune. It's also a smidge less torque than full Stage 2 E85 which over time has proven to be pushing the safety envelope. I only takes one early upshift to load up those roads at full TQ which will eventually result in a windowed block.


I understand we are all power addicts but to get the remaining 10% from the stock turbo you need to drop thousands of dollars and it's just not worth it. This is similar to trying to retain a warranty by modding a stock tuned car. The combination TCU, ECU and E85 tunes make this car special.

[ourlee]

If you want more noise, get a DP and tune with a removable, non warranty voiding JB4. Don’t do what I did, I did a res delete and REMUS axle back, sounds great but zero performance increase and WAY too loud if I installed a down pipe. For whatever reason, no one wants to buy my REMUS so I can bump to stage 2.

[BeTTo RS]

downpiwpe, midpipes, inlet, intake, and still hoping to retain your warranty?

For me, that’s really a basic mod and IMO shouldn’t avoid any warranty. Without tune you’re not drastically changing its performance.


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[BeTTo RS]

What stops the car from adapting to an aftermarket hf downpipe?
My 2017 Golf R had just a HF 200 cell dp added on a stock tune, and there was a power increase.
It was much more noticed when I removed it (prior to trading for a 2018 RS3), but it never overboosted or had any drivability issues, just it feeling signif responsive and it was butt dyno faster.
Oh, I also had a dry aFe intake drop in filter as well.
There was a minute when it was much more modded prior to the above, (when I tried tunes, a JB4, etc), but I digress.

Why doesn’t this car adapt and enforce control to changes to like what the OP wants to do?

I started with bolt ons ons with my ex VW MKV & MKVI since I was uncertain on which tune to go with. And no CEL with both having Miltek 200 cells catted downpipes… I guess those ECUs were less sensible to these changes.


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