I have Hooker Super Comps-P/N 2131. Fit is okay-had to dimple near the p/s box on cyl. #3 tube, and at the pitman arm. I've seen some posts that state the right side header hit the idler arm. Never had this problem. Also the left collector flange hangs a little lower than the right. Just a side note- I put a set of headers and dual exh. on a 1970 z/28 I had while in college. The power difference was night and day (felt like I put a blower on it). They may be a headache to install, but are well worth the headache. Probably a true 35-40 horsepower improvement.