Fast, low-cost N52 exhaust project.
Current setup:
-AA replica headers.
-54mm / 76mm custom exhaust, slightly shorter mid pipes than stock.
-Some a "BMW" resonator, I think it's from a car with a 328i N20 engine.
-135i (N54) muffler with custom electronic flap that bypasses the muffler.
-No catalytic converters.
-I painted it black, but it's stainless steel.
The sound is awesome too with the flap closed. Creepy scream when flap open... Slightly resonance at 1800rpm, this was also the previous Supersprint exhaust. The resonance disappears if the front cats or middle cats are in place. There is no drone.
I also have a straight pipe to replace the muffler. I haven’t tried driving this yet, but it’s really loud when I tested it while the car was being lifted.
Flow testing when flap is closed and opened.
