15percent on the z, weekend car though, my previous mercedes had 5% all the way around with a black car that i drove daily in westerville no problems.
http://i158.photobucket.com/albums/t99/evogarrett/Picture1188.jpg
It kinda looks big but its not, its on jack stand to perserve the tires, cabin space is 4x7x4
http://i158.photobucket.com/albums/t99/evogarrett/Picture1555.jpg
http://i158.photobucket.com/albums/t99/evogarrett/Picture1554.jpg
http://i158.photobucket.com/albums/t99/evogarrett/Picture1553.jpg
http://i158.photobucket.com/albums/t99/evogarrett/Picture1552.jpg
600
Very true it is, there are some members on here that can personal vouche too as I can too, though a reliable tune, maintenance, correct psi, fuel and more. All are necessities to keep your 4g63 running strong at 500.
2 years ago i had slomo fab me a 35R kit for my evo, stock head, stock buttom end, i reached 506awhp with ease. I would now go to ips reguardless of my car for your 500 goals, im sure you know that though, either way good luck man.