i was at the speed shop today discussing options i said that i was going to buy a used h pipe or x pipe if i could find one to bolt up instead of the stock 4 converters to get the full use out of the flowmasters i have welded up in the stock locations that seam to do no good with stock everything else exhaust. he then told me i couldn't do that because it throws the computer into wacko land i think because o the 4 o2 sensors, but don't quote the last part, i just know he said bad move it will make the car run bad. i felt kinda lame, but everyone here runs some sort of h or x pipe right with no problems i think. help is he right? and why? or not? and why?