I have an 84 IM on a bug pan. With the shorter offset type 1 manifolds that came with the CB DRLA kits. With those a vibration damper (1/4"), 45 DRLAs, hex bar linkage plate and K&N filters I have no more than 1/2" clearance to the engine lid. I couldn't fit the long type 1 manifolds or the non-offset. The newer IMs have the engine moved forward which gives a bit more space.