That maybe the problem. Just messing with for a little bit today, if I play with the heat shield on the cat at all it sqeaks a bit. I guess I will just wait till my hi flow cat comes in and see what happens. And the heat shield is coming off the cat tomorrow. Oh and another thing is it ok to not have the stock heat shields on the new header? My engine isn't running any hotter so I dont find a problem with it but maybe other parts in side the engine bay may not like it, any comments? Thanks