Yes, I have a 4-2-1 Greddy Stainless header with a magnaflow high flow cat that I installed a few months ago and whatever cat-back system the car had on it when I bought it. I don't know if it's always been a problem because I haven't had the car that long. You think some of that heat wrap from the parts store around the header and possibly the cat may help? If I'm not mistaken, I do believe the area I'm feeling the heat at is about where the cat sits. The car does have a heat shield there, though.