well, if the car revs but isnt making more power, thats one sign the clutch is gone... ive never had a clutch go on me, but it would be like your tires spinning (car revs, not going faster)
easiest way to tell is to put it in 5th gear and lower rpms and mash the pedal to the ground. If it starts to rev but not pull, the clutch is gone... but thats already happened to you.
thats really the only thing i think it could be. If you are hitting full boost, there should be no reaon you shouldnt be making power (unless theres something horridly wrong with your engine, but you would know it if that were the case) Maybe some wild tuning problem, but again... i think you would know it if that were the case