Have 72 SS 402 Camaro. Installed hooker 2455 headers and the left side flange touches the floor board and the right side has about 3/8" clearance between floor board and flange. Headers bolted up no problem (after modifying the flanges to fit around arp head bolt heads) and are not touching anything on left side. Opps! not true, I might add I had to trim part of left side motor mount corner so as one tube wouldn't rub. Other than that nothing touching on left side what am I doing wrong? Any advice would be helpful.