I used the Magnaflow 11226 on both my 98 D1 4.0L and my 02 D2 4.0L. Both with resonator deleted.

 

I live in Florida and have no emissions/inspections requirements on any vehicle.

 

I had clogged cats and no emissions testing so I got all of the fluff and cake out of them with screwdrivers, mallets, and whatever I could find, and a throw away vacuum cleaner.

It sounded so bad I bought a new exhaust.

When our cats are empty the exhaust sounds like a glass bottle skipping down a driveway. Horrible. But I left the cat housing in place to pass visual inspection (even though they never look).

If I did it again I'd put pipe in place of the cats. The trouble on the passenger side is that the cat inflow and outflow pipes are offset, so you'd have to be fancy with the pipe unless you want to make a big, obvious change. One advantage was that it moved the heat of the cats away from the driveshaft.

I'd get rid of the resonator, put a Flowmaster muffler on, and a side out (through the body panel) exhaust. I'd do all of these things with you but my love hate Disco relationship is in the hate faze right now.

I didn't notice any change in power or mileage when mine were gone.

 

Charlie, the way you did it I pretty common but will absolutely kill exhaust flow. It creates tons of turbulence. To do that correctly you actually need to cut the cat in half and weld it back together with a piece of pipe running through the inside.

Also, I will say that it does in fact sound horrible catless with the stock muffler, but if you throw on an aftermarket muffler its like the voice of an angel.

And Best4x4, its important to note that a de-cat will make the exhaust tone MUCH different. While I'm sure the Magnaflow would still sound very good, it will be quite a bit louder and the tone will be almost entirely different.

 

Cat's removed from anything will make it sound/smell completely different yep. My 98 D1 had a cat blow to bits, and once it was 100% hollowed out it sounded like I had a massive exhaust leak right under my feet while driving. Replaced the bat cat, and it went from sounding like a muscle car with a trick cam in it to a normal sounding V8 with an exhaust on it.

 

Rock Auto has a Davico cat for $336 shipped. There is a 5% coupon online you can Google. Just enter the code for the discount. I ordered mine and they are simply bolt on. I think the Davico is one piece and I have to remove my front crossmember, but my underbelly is a mall queen and clean, so I don't anticipate a problem. Other cats come in two pieces to simply bolt on. Just an option.

This is what I'm using. RockAuto

 

I should add that I also removed the cats (the whole y pipe was trash at that point anyway) and put flex pipe in their place. It made the exhaust floppy and, as Best said, sounded like a huge exhaust leak. A solid pipe in place of or inside the cats it the only thing I didn't try and, most likely, the best solution.

 

It's like that here in France. I've removed all the DPF's from my trucks and put straight through pipes in place of the center muffler on the D2 and it gets tested every 2 years and not a word is said. Mind you when you see some of the old crap that goes through and is passed by the inspectors it makes you think

I should also say it's a TD5 engine.