I have found that exhaust/engine heat is a considerable factor. You may want to look at insulating the underside of the clam shell with shielding and the rear bulkhead. In my case and in addition to ceramic coating the headers and mufflers, there was a need for Inconel heat shielding at the shock towers and along the frame parallel to the cylinder heads. Even with all that, I hope that I don't get stuck idling too long in traffic as the air flow is critical or the motor is going to struggle to get air.