So I have searched around and I see some horror stories...I have a 94 z28 M6. Its pretty much stock, very simple stuff...im looking at a set of Nitto 555R's...the car won't be dragraced that much, but it will some...the rear has 136k miles on it...how scared am I of blowing it? Its a stock clutch btw with like 1500 miles.

Also, how much would it cost, labor and all to put a 12 bolt in the rear? Thanks.