These are muscle cars right ? And with one of your medium powered motors in them, the bodys dont flex ? Not so much the bent panels just the paint starting to crack. I was refering more to the older cars that had a seperate chassis. I had a 38 shev coupe once with a blown 454 chev in it, and when I put my foot in it it used to pop the doors open from the torque and get rubbing where the panels met and cracking paint, especially on the firewall where the mounts bolted onto the chassis.