Stroked91

i just recently purchased a 99 cobra i have a couple questions.
my car obviously came facotry with the irs so i was thinking of getting the maximum motorsports grip packeage mmrg-21 . was gonna get driveshaft shop either stage 2 or 5 axles. and i was thinking of getting a 03/04 cobra dif cause the stage 5 axles are 31 spline. one question is how much power can the 28 sline dif handle and if i was to get another dif all together what would anyone recommend. im only lookin to push about 500hp or so. any help would be apreciated thank you