[D-Bo]

actually i think the stock discs will work.. all the brake upgrade does is increase the friction area really.. the 4 pistons do help with psi but unless you're doing autox then it wont really matter.. bigger discs would make a difference but you wouldn't really notice it on the street.. braking will be more efficient with larger discs so its your call if you want to spend the money or not.
and if you're keeping the stock rims then you'll need spacers cause the calipers won't clear the rims