Tuning is HUGE too. The quickest way to grenade an engine is a flaw in the tuning. If you try to do it yourself without fully knowing what you're doing or have a budget tuner try to do it, you're begging for problems. My car has been tuned and retuned by one of the most highly recommended Subaru tuners in the states. I wouldn't trust my car anywhere else.
Yep... First guy to get 1000 HP out of a Supra 2JZ-GTE on stock internals said the key is PERFECT tuning.
I spent $700 at the dyno just getting the WOT maps tuned on my MR2, and then I self tuned the mid-range maps. She put down 290 hp at the rear wheels and 290 lb-ft of torque, and I heard a few weeks ago from the guy I sold it to it's still going strong.