Good luck mate, sounds like its beginning to come together.
I wouldn't suggest going to the Dam run with no exhaust, could cause you a lot of grief, not to mention create a mess under the car.
from here on in I only have one hint of advise for you;
Take your time and do it once! It may feel like it's taking you longer to build and get running, but in the long run if you slow down and spend the money wisely, it will come together faster, cheaper and better than it would doing it with cheaper parts and rougher. This will only lead to spending more and doing things two and three times. Believe me when I say it will be well worth it in the long run!!
Once again, good Luck and just keep chipping away!