These headers bolt perfectly to the engine, although they require a couple of bolts and a socket wrench rather than a socket to access them. After installing the engine, I found that it didn't fit the factory exhaust system. The exhaust pipes were about 4 inches narrow and an inch lower. In the end I had to shorten the exhaust system, lengthen it and weld it back together. For those who just want to screw on the screws, this won't work. I would recommend for those who don't have the facility to swap out their muffler take them to a muffler shop to have them fitted so the muffler can be rebuilt at the same time.