while in neutral or in gear...with out moving.---I start by reving the car up to 2000-3000rpm and i let off, around 1000-2000- rpm the engine knocks or stutters a small noise

my engine has good compression...turbo is good----it all started when i dropped the clutch on a burnout and all the sudden it started doing that...i dont know if its the tranny, loose exhaust... but it only doest it low rpms

 

If it's a rattling noise, the exhaust port inserts may be the cause. It's usually noticeable when the rpms drop.

 

is it bad