This estimate seems too low. I read that the 03-04 Cobra is underrated. The actual rwhp is around 370 (or 435 bhp). Since the Cobra responds well to exhaust mods, he probably gained 25-30 rwhp with the mid-pipe and catbacks. His intake mod probably added another 10 rwhp. The Predator, if used in conjunction with a dyno tune, should squeeze out another 15-20 rwhp. This should put his Cobra at 420-430 rwhp. If you look at the signatures of other 03-04 Cobra owners with similar mods, you will probably see these numbers.
Yea, I dyno'ed my bone stock 03 Cobra at 374 RWHP. If you add those mods you should be well into the 430 RWHP range. If you can get a good launch and shifts you'll run low 12's easy.
I have the #'s in my sig from a FIPK, catted X pipe & catback. So with a tune you should get even more I'd think. I'll guess around 420 rwhp & 390 rwtq.