IMHO you are always better to use the best manifolds for the car you have. There is a reason they were made specific for your car. Generally the older the better, exhaust manifolds got pretty ridiculous as time went on. You can buy ready to go exhaust and use factory tips and hangers. Otherwise you are reinventing the wheel all the time, and for what gain? All that time and finagling for a small gain, I just don't see the point. Or just spend the money and get custom.