Another thread about exhaust system

[bcdesigns]

Sorry for another thread about exhaust system.

I want to bypass my cat and remove the center muffler but will be a better mod if i install 3"pipe instead of the stock dual pipe... i spoke with a tuner here in Portugal and he said me that here nobody make exhaust pipe SS with turns bigger that 65mm (2,5")... So, i sent a mail for longlife ( awesome works) but they need my car to exhaust...
I searched for brand system, but i only have Supersprint (almost stock on look), Milltek just for s2...

I only see one solution, is bypass the cats...

Somebody have a better opinion???? Or know somebody that could help me?

oh my ride is a S4 avant...

[Greg_S]

If you are just bypassing the cats and not looking to fit a full system I would go for a set of off the shelf bypass pipes since back pressure will increase if it goes to 3" then back to standard size because it will expand and then be constricted back again disrupting the flow.

[porkkis]

http://www.bn-pipes.de/edelstahlauspuffanlage-dateien/edelstahlauspuffanlage-audi/audi-s4-s6-s6-plus-type-c4-edelstahlauspuffanlage.htm

That's a 2x60mm system, but 3" = 76mm -> ~4500 sq mm and 2x60 -> ~5600 sq mm

So preferably 2x60 and not 1x3"

[bcdesigns]

I didn't know that the stock system is 2x60mm...

Thank you guys.

If i understood, the rigth way is (i thinking one of this):

- Stock Downpipe, cat-bypass pipe, bypass the frontsilencer and let the rearsilencer.
- Stock Downpipe, bypass the cats and frontsilencer with 2x65mm pipe and use a custom rearsilencer.
- Custom downpipe, 2x65pipe just with one silencer on the middle and a vented wastegate.

What you think, i want a little more hp and some noise.

[porkkis]

I think the stock urs4 pipe is 2x2".

I would probably buy the bn-pipes as the price is quite right IMO.

[bcdesigns]

yes, its a good ideia and awesome quality, but i want some hp and some noise, just this bypass pipes will give me that?

Cheers
Bruno