Your replay peaked my interest and I had to go dig out an old AMT '64 Impala SS from the stash. You are correct about the exhaust manifolds being in the kit. There is also some nice headers in the chrome tree. I now think this detail has to do with AMT providing the wrong exhaust manifolds. Mine is an older issue #2203 on the box, the instruction sheet is starting to yellow. The instruction sheet depicts the kits manifolds, although they are incorrect for the engine in the kit. The W engine exhaust ports are at a different angle on the engine than the small block and a somewhat different shape on the 1:1. Also if you look at the engine emblem on the front fenders this is for a 327 cu.in. engine. The cars with the 409 engines would have had the numbers 409 above this emblem on the 1:1 Since they didn't offer any decal to depict this makes me wonder if during the design of this kit years ago AMT was thinking of offering it with the 327 engine instead of the 409. Revell's '64 Impala SS has a 327 engine when it was issued several years later. All that aside you still have a great looking build going and I only meant well in mentioning something that I noticed.