You don't have to worry about the car being loader, unless you mod the catback and as far as heat, I don't think it makes a lick of difference between the stock manifolds and headers. Here is a link to SSAutochrome these are the ones that speed daddy copied Pontiac Performance Racing Products for International Sales from SSAutochrome Inc. $175 plus shipping. And idk if anyone told you yet but with those headers there is a ubend in the downpipe that will most likely hit the ground if you go over bumps. I tore a hole in my dp when I had mine on. There are a few threads with instructions on how to mod out the ubend and since you can weld it should be super easy to remove.