Boys,

I need some input.
Recently I've been noticing a vibration noise on deceleration from around 4k, to me it sounds like a vibration from around the x pipe, but after pulling all the exhaust off its sounds like its coming from out of the headers.
My mechanic said it could be caused from the firing order but I'd like to know if its a known fault.

I'm taking the car to another mechanic to see if he can fault find the issue.

They also thought that it could be caused from the VVT solenoid but we removed the plugs and the problem still happened.

I only noticed the noise once I install Stillen Gen 3 long ram intakes and AAM Competition Front pipes.

Car is a 2007 350z Track with 52,000KM/s

Current mods are:
Dual 2" Custom stainless steel exhaust
Extreme heavy duty clutch with single mass flywheel
AAM Competition Front pipes
Stillen Gen 3 CAI
Uprev Tune (Made 200rwkw)

Please help, this is doing my head in.

Cheers
Kyle