Ok my neighbor just bought a 350z and it has Stillen true dual exhaust, stillen test pipes, and stillen headers. He also has injen cold air intake, plenum spacer. However his car sounds really high pitched/raspy like that civic vtec sound. Would taking his stillen test pipes out and putting the catalytic converter back in be a good idea? I looked on youtube how stillen exhaust sounds and his setup doesn't sound nothing like them.

 

The reason for the RASP is test pipes. Either put stock cats or resonated testpipes / high flow cats. Or you can install a magnaflow x pipe which elimnates all rasp and brings back the VQ tone a little bit and some torque down low.

 

I had the exact same setup. I couldn't stand the way it sounded. It sounded like a Honda with an opened up exhaust. Not what I was looking for, espeically with the Z. I put my stock cats back on, and it sounded worlds better. I would put the stock cats back on, if I were you, at least for now, then maybe getting some high flow cats or resonated test pipes.