I am wondering if anyone on here has had or know anyone that have had their HP exhaust manifolds ported and or extrude honed and if so do you feel like you gained anything? I am going to be rebuilding the 440 in my Imperial & when I do I am going to do a few things to build more power id like to get to the 450-500 hp range but I will definitely not be doing headers I just don't want the hassle of headers
