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I know there are 4 total cats on the 99-2004 gt mustangs (two precats and two main cats) My brother wants to free up some power and is on a limited budget(saving for x pipe in the future) so he wanted to hack off the precats on the midpipe and replace it straight pipe in its place. My question is will he throw a check engine light while still retaining his stock main cats?? Will there be a power increase??

 

Cut your rear cats and keep the front cats.....No CEL for about a year now.

Pre cats are TOO CLOSE to the manifold to even think about cutting off anyways

later

 

Well arent the precats more restrictive than the main cats?? Did u weld straight pipes or clamp them on using exhaust clamps for the pipe?? That is what Im thinking of doing .

 

i have a 99 GT and i have 6 cats

 

yeah, i have a friend that got rid of the last two cats before the h-pipe, and he had no problems.

 

Why would you waste a $500+ pipe when you could get an off-road H pipe for a little over $100?
-P.

 

How does it not throw a check engine light since u hacked off the rear cats?? Dont our cars comes with 4 o2 sensors?? Anyways, was there a difference in performance or sound with the rear cats removed?