Whats the rest of the set-up on the car like? It sounds like you have nothing to laugh at under the hood right now and no less power then alot of the newer cars out there. I would suggest spending some on the motor you have and then taking a good hard look at the rest of the car. Gears? Tranny? Weight? Traction? Etc. You could spend all of your money on another motor and have none left over for the rest of the car. Something to think about.