Originally Posted by FricFrac

Opposite for me - idle is weak - way to quiet. Sounds fantastic under load. The drone is around 3-4K RPM and its because that's the resonant frequency of your cabin - open the windows and you change that resonant frequency (somewhat). It doesn't matter what exhaust you have you'll get that frequency where it "throbs" like that.

Just a question - if you don't like the exhaust note why did you get a loud exhaust system? The NISMO exhaust should give you better flow and its much quieter. IIRC someone is getting rid of their NISMO CBE because its too quiet.