A realization I had while talking to another autocrosser the other day. At least 90% of the street cars that I see getting the top times are stock class cars. This holds true for most regions that I have seen as well. With the sole exception of a very well modded STX Evo VIII MR and a E30 BMW with springs and short gears, the entire top 10 in most of our events are stock class.
I also see the many of the experienced racers often sticking with stock or lightly modded cars as well. These guys have gone through tons of cars and classes, and end up back in stock. I know one guy in particular who spend a bunch on his 2004 Cobra, but then after 3 seasons sold it and now has a B Stock RX-8 that he's much happier with. 95% of the fun with 5% of the cost.
Besides, I can't think of more than a handful of people on this site who can actually say that they have reached the car's limits on their best day. Maybe after 5-6+ years of racing, and some serious national titles, I could say that the car is starting to hold me back...
Don't waste another minute waiting on parts, or anything else. Just get out there and start racing! You will suck at first, and you will be slower than many other cars, but the only thing you will regret is not starting earlier...