vtraudt

After getting quotes for replacing the 2 leaky flex pipes (shock), I thought: why not install test pipe (got the 3" for the our 1.8T for $150 shipped) now, get rid of the cat (they will be needed anyway when the RS6 turbo's etc. go on).

But everyone seems to only offer fancy 'high flow cat' and complete systems at ridicolous prices ($1000 for 2 bent pipes???).

Isn't there a simple downpipe (like for the 1.8T)that goes from the turbos to the Y?

If so, can someone point me (link)?

If not, I guess I have to take the existing ones off, cut the bad flex pipes out and weld new ones in ($25 shipped for 2). At that point, should I cut the rest of the flow restricted section also out and weld in pipes while I am at it (figuring that even a stage 2 may benefit from free flowing exhaust).

BTW: what is the diameter of the stock system?

01 2.7t

If you find some well priced pipes please post where to get them, and good luck with the hunt.

vtraudt

Does anyone know what diameter and length I need for the flex pipes?

I also plan to get rid of the main cat and install a straight pipe.
(Pre cats will be gutted).

How long (edge to edge) are the main cats?

sugaryling

I'm using 2 OBX 3" resonators in place of the cats. They're stainless steel. Got them for $25 each on ebay. $75 for 2 includes shipping.

Before the OBX resonators were installed the car was waaaay too noisy for me. I have 3" downpipes to an OEM RS6 (non sound enhanced) exhaust. No cats at all.

vtraudt

Are you saying that the stock RS6 exhaust with pre or main cats and 3" downpipes is too loud? I am not sure how it looks like, but assume similar to my center resanator/crossover pipe plus 2 muffler.

From on source I heard that eliminating the pre and main cats, from the stock 2.7 (S4/Allroad/A6) system does not change the sound level much.

Diameters: I ordered 2.25" flex pipe with extension, and 2.25" 'slip joint clamps'.

I measured 2" OD of the pipes after the cats, but 60mm/2.25" OD before/after the flex pipes.

Plan to:
- cut where the downpipes are 'down', before flex pipes
- cut after the cat, but leave some pipe left (1-2") to allow coupling or slip clamp in case I want to install main cats again
- slip clamp flex pipe to downpipe
- take measurement for required length and bent of connection pipe (end of downpipe to 2" after cat pipe)
- weld flex pipe to connecting pipe
- install flex/connection pipe using 2 slip clamps each for test fit

- remove front slip clamps
- remove downpipe turbo flange bolts
- remove downpipe from car and gut pre cats

reinstall

Enjoy finally quietness.
Enjoy faster spool up and less back pressure
Retune car to take avantage of lower back pressure

sugaryling

No, I am saying that the stock RS6 (non sound enhanced silver tips) WITHOUT ANY CATS AT ALL and with 3" downpipes is too loud. There is too much drone when driving in the lower RPMs. When I'm at WOT its too loud for my taste.

I fixed the problem by adding to the existing system a 2.5" X-pipe and two OBX 3" resonators at the main cat's location. With this setup, now the car sounds stock (well at least 95% close to stock). Just the way I like it. It does smell a little when you're at a stand still because there are not cats at all.

Ryoga28

Will there be an x-pipe kit for 2018 s5 sportback?