BMW 3 Series Forum - Technical Talk on the BMW E21
After "modding" my airbox, AKA cutting a hole in the side of it, I can now notice a VERY distinctive change in induction note at 4500RPM. It's really noticeable, it's like VTEC crossover nearly.
I'm not sure if theres a power gain when it happens, maybe slightly, but I was just wondering what it...