IMO I wouldn't lower the X brace like that. And if I did I wouldn't brag about the clearance like on that web page. If you have stock manifolds you might as well put a stock dual exhaust on it. I have stock manifolds and exhaust that tucks up in the tunnel. My car still has plenty of performance and I have lots of clearance. I bet you will not gain any more than about 20HP between those headers and X pipe and my stock system. If you need the 20 bones that much then go for it!