what slider has said is unfortunatly true. My Prochamber does make noticeble power above 3500RPM, but quality of material is some what disappointment to me. I have coated with header paint(few coats), and so far everywhere else except weld is rust free. Weld developped miner serface rust. Nothing bad, but considering I don't drive my car in rain, I must say that rust is disappointing. But sound it makes with Magnaflow is something else tho. i even get complment from Chevy and Pontiac monkeys. I have my PC off right now and have stock H on, to get my car serviced, and let me tell you, magnaflow makes our car sound mean. But you just wait until you put PC on. Very unique, yet unmistakeblely Mustang. I had BBK X pipe on befor, and hated it. I would recommend PC to everyone, except one lives in northern region where they drive car in winter