While all of you people were out showing off your cars and chatting up the ladies at wasaga, SOME of us were actually at home, in our driveways, under our cars working on them.
So, the mod that I did today is the "butterfly valve actuator delete" or as its commonly reffered to as "the golf tee mod".
Peices: Golf tee
Requirements: have to be able to get under car (if you have an aftermarket diffuser this is slightly, but not impossibly, harder)
Pretty much, what you do in this mod is delete your butterfly actuator valve. The "purpose" of this mod is that you gain a slightly deeper/raspier exhaust note under 3000 RPM.
The butterfly valve works by vaccum. so:
1. jack up car (if lowered, my sport package 328 didn't NEED to be jacked up, but i did it anyway to act cool infront of neighbours).
2. Unplug hose leading to the valve. (diagram below) #17
3. Insert golf tee into hose to plug it.
tip: If you insert the tee from underneath your diffuser through one of the stock holes, and plug it from the top, the hose/tee wont rattle. This may be different on stock diffusers (i have the m3 diffuser).
Results: Car sounds meaner, not quite ricey but getting there. I was reasonably satesfied with the gains, particularly from 2-3K RPM.
until i drove the car
Now i knew this would lead to some torque loss, but WOW, my car made me want to
I mean 328->325 torque loss. It was significantly worse, particularly off the line. I was aware that i would experience some torque loss, but i did not expect anything this severe.
Car went back up, everything got plugged back in, and I was having fun driving around with my regained torque.
(until i ran into mcgyver at the local partsource, with his s52 325is, and was reminded how slow my car really is
, but that's a story for another day)
Would I recommend this mod? No, not really. If you're particularly concearned about your exhaust sound, or want your car to sound specifically meaner between 1-3K rpm for a short period of time, car show, etc, sure. But honestly, its not even worth the torque loss to implement this as a temporary solution until getting an aftermarket exhaust.
Why do the write up? So people know what to expect
(BTW this mod ONLY works for 328's, i dont believe 318's,325's or m3's have said valve)