We think the motor is toast in my cousins coupe.In a nutshell,very bad vibration only at 4000rpmsand up,other than that very smooth,thought it was a clutch problem,put a Spec stage 3 in with new pressure plate and a billet steel flywheel,not the clutch.Also the tranny (TKO) bearing retainer was broke,fixed it also.Still the same vibration at 4000rpm.He also checked the balancer and no signs of spinning,and it's in the same place as installed 2 months ago.And ran the motor without the belts on,same.It does it weather the clutch is in or out so it's not coming from the clutch back.We gonna put a different ballancer on it tonight just for piece of mind before we tear the motor apart.Were starting to think it might be a rod possibly the crank.Any idea's.The motor only has about 600 miles on it. Thanks