If you look at side pipes they run 3/4-1" away from painted fiberglass. Headers run 1/4-3/8" away from glass foot boxes on some cars. I wouldn't be too worried about a big air gap, especially as it gets further from the motor. Couple of pics attached. I have the street car fiberglass exhaust loop covers if you need them. You can see them here and in the attached pic.
Spare Tray/Wheel Well 427 Trunk [] - - It's Free! : Acton Custom Enterprises, Custom Metal for Cobras
