Hey guys I have a 2007 350z HR, I drove the car today and noticed something new, Once the car reaches 5000rpm the shifter starts shaking like crazy and makes a clunking type of noise. Sometimes this happens sometimes not. I havent been able to find any forums or videos online for this.. happens both when in gear or not. The modifications with the car is a clutch with lightweight flywheel, has stillen exhaust, stillen gen 3 intakes also the stillen shortshifter.
Any ideas what it could be? really don't wanna do a tranny rebuild Any input will help.
Thanks

 

Get under the car and start inspecting all the rubber mounts that support the engine and drivetrain, front to rear. Replace the bad ones.

 

but basic troubleshooting makes too much sense....