With only $500 to spend, I think you will get the most bang for your buck with a stadium truck and the truck that best fits your criteria would be the RC10GT. I don't recommend it because if its performance, but because like Speed Demon has already posted, it has a ton of available hop ups.

For a few dollars more, you might want to consider the Hot Bodies Stadium Pro. Its not a stadium truck. Its a 1/8 scale buggy with monster truck 'A' arms and wheels. I think it would be the ticket for big speed and huge air.