Supra Motor Vibrating???

[supragirlmk3]

Hi so my bf has a 89 supra. The 7mgte motor was completely rebuilt by rebellas, it's a five speed turbo. When his car reaches 4000 rpm the motor starts vibrating(the speed doesn't matter) as long as it's past 4000 rpm it'll vibrate. His clutch is an eBay stage 2 XD or something, im not quite sure which one exactly, and his tranny isn't very good, sometimes second gear pops out. Also he needs to change the wheel bearing in the driveshaft and his rack and pinion is a little messed up. (I'm just giving any info I can so u guys get a good sense of what the problem might be with the vibrating)
any input Is helpful! He's getting his car tuned over in santa rosa this weekend and we need answers asap, so any help is appreciated! <3
Oh and the clutch is supposed to hold 390 HP. ( I don't kno if it can handle the power. The supra is at least 350) if u n?ed any more info let me kno!! Thanks!
oh and also he can shake the right front tire, side to side which is baddd, but i dont think it has anything to do with the vibration because we found out that, like i said, it only vibrates after 4000 rpm, no matter the speed of the car.
Thanks again <3