Exhaust ?s (not size or header related)

[sudo chop]

Straight to it - The exhaust shop has me convinced that running a non OEM cat will result in a CEL, but the guy has told me he can put a cat on there, for $300, that he can pretty much guarantee won't give me a CEL. I had a 3" collector put on my APN header, which I regret now, but I am likely going to have then run 2.5" down to the cat anyway. I've already got a super 44 in the mail and ordered the rusty's 2.5" tailpipe.

So having said that, I am just wondering what catalytic converter everyone else with an OBDII jeep and a stroker has run, and if they have had any problems with CELs.

I am sure as hell not going to pay this guy $300 for a chopped up cat if a $100 magnaflow direct replacement, or some other cheaper one will work fine. I figure the O2 sensor in the cat is looking for a certain amount of O2 to make sure enough of a reaction has taken place in the catalyst? Correct? Thats a simple enough task.

If it seems that I'll be ok with a magnaflow cat or something, then I am thinking about doing everything myself besides having them make the custom head pipe and put an O2 bung behind the cat. Does anyone know if a mandrel bent 2.5" head pipe exists for the cherokee? Seems like it would be much easier to have then modify one than make one from scratch. Its all about keeping a little more $$$ in my pocket.

[Alex22]

I'm still running the stock 4.0 in my 96 XJ and I just installed a Magnaflow direct fit replacement (I don't think Magnaflow is the OEM supplier) and a cat back exhaust with no CELs. I don't see why using a larger than stock cat would cause a CEL. If the larger cheaper cat throws a code you could always modify the signal back to the computer by adding a resistor or possibly a voltage divider.

~Alex

[SilverXJ]

Find another garage. They are trying to rip you. Get a maganflow high flow for ~$70 or so.

[IH 392]

The OBD II on your '98 shouldn't throw a code, my '97 has a gutted converter and a GIBSON cat back on it and it's NEVER offered to throw a code in the last 7 years!?, don't know why functioning converter would throw a code?

[sudo chop]

Well, I feel pretty comfortable getting the Magnaflow cat now. Thanks everybody.

For anybody who's had custom exhaust work done, how much should I expect to pay for a custom front pipe? I couldn't seem to get an estimate out of the guy on the phone.