hey, my friend just finally finished breaking in his xxx-nt sport and he was doing some wheelies. about 5 minutes later, something weird was happening. if he gave the car hard gas a strange and loud grinding sound would come out. clutch is good, and sometimes like if he revs the car up and my foot is in front, the car wont move at all after unless we give it a little push. the dogbones or CVDs look pretty good. could it be the drivetrain?