Catalytic Converter

[5SpeedPony]

I have a flowmaster super 44 muffler on my stock 03 mustang exhaust. I still have the low-flow catalytic converter on. If I cut the cat off is there anything that could go wrong? Like the O2 sensors?

 

[acsthacker]

My biggest concern would be the lack of back pressure. I know when I put my 44 on, the back pressure changed and now when I push the clutch in while driving the RPM's go up quite a bit. Not sure of the fix for it but I'm hoping the tuner I get will give me some options to affect it.

 

[wmburns]

Note, if the RPM's go up when the clutch is depressed, there is too much air entering the motor. Either there is a vacuum leak or the throtle body idle set screw is too high.

Check out for more idle and IAC trouble shooting tips.

Is your mustang stumbling, dieing at idle or idling rough? - Page 14 - Ford Mustang Forums

 

[5SpeedPony]

So wmburns, what you are saying is there will be no problem with my car whatsoever if I hollow out my cat?

 

[jrod2423]

well the only problem that could occur is there isn't enough back pressure and the valves don't stay at a constant tempature they will go out real quick, and also i think mustangs have 4 catalytic converters on them or at least 98 does, but you just need to make sure that you have enough back pressure to keep your valves hot so they don't warp from the heat and cooling proccess of no back pressure