I have yet to have problems with any of my Z's except im rebuilding the tranny in one of them I have 3 Z's. If you buy a Z in bad condition don't expect to fix it. If you buy a Z like my white Z all taken care of and all work done. You won't have any problems. Also I don't care how much money you put into your car your not going to run 10's if you can't drive worth a sh*t. Im not saying you can't but im just trying to prove a point. You still want to sell you Z and get a supra? go for it I don't think anyone will stop you but make sure thats what you want to do. Because If I had the chance I wouldn't trade my Z for a Supra. The Z is a much funner drive. I know trust me.