If you have a decent amount of hp, and sticky tires on the back, you will more than likely need a 12-bolt soon. I am pretty sure once your friend starts modding, he will have plenty hp. With the M6, if you get on the gas too hard off of a stop, you might break the stock rear end. The best thing to do is, start modding it, and if you break the rear end, get a new 12-bolt.