depends on how much risk you wanna take....according to "the book", u should replace them and loctite them every time they are bothered.....on my own cars, turbo and non turbo, i have just reused them, but i was broke and needed the car, but had no problems....if you can help it at all, then buy new ones....u dont have to get studs, the are just supposed to torque better than bolts......the car i reused them on was an 85 xr4ti running 20 lbs of boost and making just under 322hp to the wheels with a t3/4 turbo and I/C.......it had to be replaced at least once every 50K miles anyway, so i also knew it would be coming off soon.....i had the head off of it about 8 times in 2 years, and it was my daily driver...but i was lucky and i know it, so just replace if at all possible.....i'm a little better off now, so i doubt i would take that chance again, if i had the car