Ok alot of great advice here but i should give the application they are for. Its a 71 superbee 383 with a/c. The engine has a couple of things done but nothing huge. I was thinking of having headers to keep the engine cooler. On my 70 cuda I had a set of rusty cheap headers on the car and it ran awesome and never heated up driving or at idle. I decided to put hp manifolds on the car and new exhaust. Afterwards I noticed the car ran hotter and there was alot more heat under the hood after the manfolds were put on. Because this superbee will be a nice summer driver with a/c (factory a/c stuff) I am trying to keep the heat down in the engine bay. So I don't have to worry about getting stuck in traffic.