Take your 500 and tack on another 3000 for a GSR swap and some suspension parts. That way you can still have a decently quick car, you still won't be able to beat your friends WS6, but you'll take some of the normal cars out there. If you're so content on beating him, then boost the GSR motor that you swap in. Also take everything out of your car that you don't need, a/c, power steering, everything behind the driver's seat should be taken out and thrown in a pile. Doing this will make your car lighter and be able to accelerate a little faster. After you do all the things I listed you might have a chance to beat him with a good launch