I would just run the tougher aftermarket 28 splines. my car is not ungodly fast, but does put about 285 to the wheels and i am running stock rear end with a t-5, pro 5.0, and aluminum driveshaft .
I think stronger axles are needed whenever you launch on some sticky tires. You're living a daring lifestyle launching with any sort of power on stock parts. I really wouldn't want to land on my undercarriage when an axle breaks and I lose a wheel. It'd be even worse when it puts you into the wall at the track.
I agree with Stang. Anytime you put a decent amount of power on stock parts and a hard launch...either your gonna leave the track on a rollback, or your gonna get lucky and drive it home. Is it safe and dependable running stock axles with 300+hp, NO...can it happen...many will tell you Yes. I can tell you that my car was run on slicks with 4k launches with over 300hp and my rear is SHOT! I'm upgrading to a full 31 spline rear this winter with 5 lug. Just my .02.
I've read up on some 28 spline after market axles that claim to be 33% stronger from summit racing...I think i'm gonna go that route since it's an aod car an just gets the foot launches. If i were doing a strip only car that that would get 4K launches on slicks i'd get the 31 spline moslers, lately i've been thinking of building it up more for handling than for strip use. thanks for all the input. as always this site has the best members for answers.
It would be better just to upgrade them. Iam running just 28 spline Mosers and they were fine all last year. Moser said with my rear gear and tranny first gear they would handle my torque. Around 440-450 ft/lbs. When I go the next step(not for awhile) chances are it will be 33s and a spool. But that would be around 1000 rwhp. Depends on your future plans, but it sounds like for now aftermarket 28's are fine. Basicly if you break a axle there is a good chance you will wreck the car, and possibly get hurt. Just a thought!