I have raced auto and manual. I put multiple cars on the manual. I put bus lengths on the auto. If your GSX really is 500whp, it shouldn't even be a race. My GSX is an auto and even in RWD territory of doing it from a roll instead of a dig, it's not much of a challenge. Brake it in, have a friend race you from like a 50 -120 and you should be pleasantly surprised with the dsm.
500hp dsm is nothing to scoff at. I raced a girl yesterday in a new black 5.0 w/ green racing stripe, black rims, dark tint, and ready to party. (The specs on the 5.0's and SS are pretty close from what I have seen). First race was from a 60 punch. She got the hit and I put a few cars on her pretty quickly. The next time she was like 50 yards back and I saw her coming up fast. She wasn't slowing down, so when I saw she was going to blow right by me, I floored it. I was doing about 60 when she passed me at 80+ and still WOT so I punched it. I had to chase her down but I reeled her back in and put about a bus length on her. Then looked down and speedo was buried at 140, lulz. the point being, even when some of these V8's get a running start, you can still chase them down and beat them.
Don't take this as me hating on V8's. They look good, sound good, and have a lot of potential. But don't sell a 500hp DSM short. You may be surprised how much faster your $8000 dsm is than your $40,000 V8.