[mp411]

aloha all,
i drive a f10 535i,
my question is does it make sense to add a down a downpipe without upgrading my exhaust system as well. Will adding a downpipe alone add any significant gains?

while im here
what can one expect with jb stage 2, upgraded downpipe with full exhaust upgrade as well.

thanks all!

[r33_RGSport]

@mp411
It is not weird to do downpipe without upgrading the exhaust system. I have done it and other done it too. No everyone like louder muffler, but everyone like faster turbo spool.
With catless downpipe, I do recommend to run it with JB4 Stage 2 to suppress the CEL and maximize the advantage of running catless.

[ezaircon4jc]

Originally Posted by r33_RGSport

@mp411
With catless downpipe, I do recommend to run it with JB4 Stage 2 to suppress the CEL and maximize the advantage of running catless.

Can you pass the smog check with that? Doesn't the "catted" one flow very well anyway?

[r33_RGSport]

Originally Posted by ezaircon4jc

Can you pass the smog check with that? Doesn't the "catted" one flow very well anyway?

Nope, you won't pass a smog check with catless. Even with Hi-flow aftermarket cat is not guarantee that you will pass smog.