The 2JZ-GTE is more than capable to hold 500hp easily. If your wanting to know more information, here are links to a couple of questions previously asked by other supra owners. Pwpanas is the guy to look to for any help regarding upgrades and overall knowledge.
http://www.toyota-supra.info/forums/...y-driving.html
http://www.toyota-supra.info/forums/...questions.html