You should be able to get a better fit -- don't give up. On mine I could never get the passenger side to fit properly and had to fabricate a hidden mount to attach the body to the firewall so I could pull in the gap. I fabricated two mating pieces, one epoxied to the lower body inside the "horns" (lower extensions under the engine side panels) and the other attached to the lower firewall. Connecting the two draws in the body and reduces the gap like you're experiencing.