Custom Exhaust

[petephil]

I have looked at getting at getting a custom built cat back exhaust system built which will be twin 2.5" pipes.
Will it restrict or cause a flow problem if after the back box the tail pipe exits as one pipe and then goes to two pipes? The standard exhaust has the two tail pipes exiting directly from the back box. Thanks

[supersi]

yes it will ..you want twin all the way to the exit

[petephil]

I did question them on this and they told me there is some sort of Y pipe in the back box so one outlet wouldn't make a difference. I wasn't sure.
If it is one pipe what would the diameter need to be to avoid any problems?

[supersi]

two in to one will slow the flow as its a sharp bend as such you realy want it as straight as pos . least restriction

[supersi]

maybe if 6" would aviod any restriction but would look <beep> i bet the y pipe in the back box is to keep the noise down i bet

[petephil]

Thanks for that. I may have to see if they can modify the back box with two outlets one six inch pipe wouldn't look too good. They have done an rs4 before and said he was running about 450bhp

[petephil]

These are pictures of two types of tailpipes. How much difference would either of them make?

[stumpyrs4]

Probably none. Aesthetic only...

[supersi]

if there both 1 in 2 out then as stumpy says