When I stab the throttle in 6th gear around 2k-2.5k (going from light to no throttle to full throttle) it sort of lurches, like something in the drive train has slop and is bouncing sort of, I just installed the jwt clutch and flywheel, so I know it's not a bad dual mass. Could it be motor mounts? I don't have any sort of bad vibrations.

 

Why are you punching it at such a low rpm in 6th?

 

Exactly. 2-2.5K isn't exactly the fat part of the torque curve, so "stabbing" the throttle pedal in that rev range in 6th gear isn't going to illicit the best response from the engine and drivetrain.

 

You are probably better off downshifting to 5th, but have you checked the rear diff bushing?