Stock exhaust mods - BMW Forum

stracer · 09-27-2005, 04:30 PM

I remember seeing something on the site about taking that vacuum hose of the exhaust

used: . I decided to take mine off to see what it will do or if I even notice anything. Does anyone know the pros and cons of this?

bitcore · 09-27-2005, 10:22 PM

less lower RPM torque, no increase at higher RPMs.
if you wanna feel a speed gain, then REMOVE the little flap.
You won't notice a difference, (there almost wont be) but thats the best you can do to the stock exhaust without drilling holes and crap.

stracer · 09-28-2005, 03:58 AM

how would u get a speed gain if u are losing torque and not gaining any by removing the flap. i would think just takin off that vacuum hose is like removing the flap

Dudesky_E36 · 09-28-2005, 06:34 AM

With the hose connected, the flap is closed below 2500rpm, open above 2500rpm. Taking it off will leave the flap open at all times, whether you plug the hose up or not. Since your powerband is well above 2500rpm, it really makes absolutely no difference, no matter what you do. Removing the flap doesn't do anything, since it has no flow resistance when open. Nothing to be gained there, IMO.

bitcore · 09-28-2005, 06:45 PM

well, it BEING there creates flow resistance, but it's negligible.
Our E36's arn't very restricted to begin with
I'd leave it alone.