Looking to upgrade the exhaust on my 2001 Supercrew 4x4. I'm thinking of a Magnaflow SI/DO Muffler with High Flow Cats. Can someone tell me what part # on the muffler I need & also the part # for the high flow cats. Do I need 2 or 4 cats? If anyone is running this set-up please let me know your thoughts on it.

Thanks!!!

 

For the cats you'll only need two. You can use either Magnaflow 94106 or 94306 for the cats. As for the muffler, it really depends on how loud you want it. Longer body cases will produce less volume. Any 3" SI/2.5" DO will do just fine.

 

What's the difference between the cats you mentioned? I take it that the front 2 cats will get replaced with the high flow cats & the rear will get deleted? So a shorter body case will be louder? I had no idea that it was 3" SI/2.5" DO. I actually thought it was 2.5" SI/2.5 DO.

 

The one has the O2 sensor bung built in and the other needs it to be welded after the cat. One cat on each side is enough to get good catalytic function. Shorter/smaller cases will be louder than longer ones. The stock is 2.5", I was suggesting upgrading to a 3" single into dual 2.5".

 

Is one cat better than the other? Will I have any codes or check engine lights come one after I install the cats & muffler?

 

From what iv read if you cut off the further back ones and leave the first ones you shouldn't have a code our anything but I just googled it so idk how true it is

 

When you change the flow past the front O2 sensors you should get custom tuning to ensure the correct a/f. During that time you can get the rear O2's shut off. That being said, many use non foulers or the Gotts O2 mod on the rears to avoid the CEL. Do not mess with the front O2s. There's no way a muffler causes a CEL alone.
The cats are pretty much equal, most use the 94106 and weld the rear O2 an inch behind the cat.