[tireburner163]

I would go with a Cobra and do a solid axle conversion(you could sell you IRS and prob. break even)

500 HP will be a lot easier to accomplish with a Cobra. A Vortech with a intercooler will go a long way towards you goal. I'm guessin a intercooler blower would put the Cobra in the 420-450 hp range(much more with inproved exhaust and intake)