Hey guys just needed some quick input. recently my muffler has started to rattle and the damn thing has rust falling from it haha. Anyways i'm buying a flowmaster 50 series for a little bit more HP and torque, plus A wee bit MPG. So i got to thinking i may as well get a new cat with it, since im sure the cat is clogged with 196k. Anyways how do the 4.0L respond to high flow cats? I mean do they throw any codes through the ECU? I may possibly in the future run boast some new headers for a little torque. Thanks for the input.

 

I run both a high flow cat and a Flowmaster 50 series on my 90, and have no complaints at all. With them, I gained back the majority of power I lost going to 31s. This is how it feels seat of the pants at least. I haven't dyno'd it. I didn't do it for the sound, but it does sound great as well.

 

From what I was reading, some throw codes and some do not. Seems to depend on the Jeep/Cat combination. There is also a few people saying that there is no such thing as a high flow cat and to just get the regular one.

This guy is a vendor on here and has one that will pass either way.
http://performance-curve.com/