This is non-intuitive but often true. If you want to race, build a car with a highly active class in your area. This will be the most bang for the buck by far and the choice of car is far less relevant. We have a lot of guys in SoCal who have more money than brains and build the "ultimate" race car while ignoring all racing rule books. The result is they get classified with Ariel Atoms and McLarens and just get destroyed every weekend. Not fun!
Go to the local track, find the active class with guys you would like to race with and build to the rule book. If you drive well you have a good chance of winning.