I'm in the process of installing a bbk x pipe on my friends mustang,now i'm having problems trying to get the header to x pipe to seal. I tried dropping it down and reinstalling a few in times order to get it to seal up, but no luck. I've installed other h pipes before but never this brand. just wondering if other people have had problems, of course the speed shop says there never been any problems with those pipes. It seems that the flange is alot bigger on the x pipethan the Mac h pipe i took off.