Optimal way to do an electronic exhaust cut off? - The Unofficial BMW M5 Messageboard (m5board.com)

jmitdesign · 4th November 2009, 00:10

Hey guys,

Not looking to debate how loud these cars should be, etc. Just looking for the optimal set up for exhaust cut offs. I have heard the two options are:

- Put an H-pipe before the secondary o2 sensors and install 1 cutoff. Better back pressure apparently?
- Install two separate cutoffs right before the mufflers?

Any opinions on what is the better option? Both are probably equally expensive as the labor is probably more intensive on option 1, but the valves are more expensive on options 2. Thanks guys

Jeff

drdre0728 · 4th November 2009, 00:13

Haha Jeff this post also goes for me. Im thinking about doing the same thing. Talked with Theo about it last night.

Cantresjr · 4th November 2009, 00:52

I believe if you do option 1 it would give you a code since you will be bypassing the )2 sensors.

I have been thinking of doing this. the way i would do it is- two cutoff after a X pipe before the mufflers, around the area were the factory resonator would be.

which cutoff are you thinking of using?

jmitdesign · 4th November 2009, 01:02

Hahaha nice Andrei! We should go together and drop off the beasts hahaha.

So doing it after the 02 sensors would throw a code? Did I write that wrong? I really have no idea what it looks like underneath the car unfortunately or what the stock setup looks like. Google images isn't really helping me either. Just figured someone must have done this before anyway and probably has a pretty good setup. Any real back pressure issues if its done before the mufflers? Summit has a cutoff package for 200, two cutoffs, gaskets, y pipes, etc. Probably doesn't matter to much with brand right?

Quote:

Originally Posted by Cantresjr

I believe if you do option 1 it would give you a code since you will be bypassing the )2 sensors.

I have been thinking of doing this. the way i would do it is- two cutoff after a X pipe before the mufflers, around the area were the factory resonator would be.

which cutoff are you thinking of using?

Cantresjr · 4th November 2009, 01:58

Quote:

Originally Posted by jmitdesign

Put an H-pipe before the secondary o2 sensors ? Jeff

from the front of vehicle you have- exhaust manifolds to primary O2 to cats to secondary O2 to a lame Hpipe to resonator to mufflers.

if you put a valve "before" the sec O2 i believe you will throw a code.

jmitdesign · 4th November 2009, 04:29

Quote:

Originally Posted by Cantresjr

from the front of vehicle you have- exhaust manifolds to primary O2 to cats to secondary O2 to a lame Hpipe to resonator to mufflers.

if you put a valve "before" the sec O2 i believe you will throw a code.

Ahh Gotcha. I think I meant to say after. I guess take out the lame H pipe and put a real one in that can have a valve on it? Does it not matter?