Wait till you hear this story. Got my 73 together with a ZZ4 and thought I'll put on some headers. No big deal popular GM crate engine, popular car, what could go wrong.......... I will list the headers I have tried and their issues. Patriot Long Tubes: Passenger collector flange hits floor board. Hedman Elite: Passenger header hits frame. Hedman Shortys for manual tranny: Cyl#1 tube will not clear the engine mount. Doug Thorley Tri-Y's: Will not clear the L98 D-port exhaust. Doug's Headers Tri-Y's: Passenger collector will not clear floor pan. Hooker Super Comp: Passenger collector will not clear floor pan. Update 9/22 Hedman 66104: #7 tube hits LCA frame pocket Patriot Shorties 8056-1: Drivers side hits frame and outlet points at oil filter Dynatech: PERFECT FIT I am starting to think my car has issues but it has never been wrecked, the body has new solid bushings, poly engine mounts (they are not higher that stock as I changed them out and it made no difference), and poly tranny mount (does angle engine up but not enough to affect headers as I swapped it out for stock and none of the above headers fit). I know the ZZ4 has exhaust ports raised .1" above stock but that is so small and it would not have made any of these headers fit by dropping the collector .1" Does anyone have a suggestion? Anyone running a ZZ4 in one of these cars with headers? I am very close to having custom headers made. It just seems that this is a very common combo and I have crappy luck.