Does anyone know who makes a high flow cat for our trucks?
Looking to upgrade the exhaust and stay smog legal...

 

This is the only one I know of. I don't think it would be legal anyway. But if it makes us feel better I say go for it. I've been thinking along the same lines.

 

I installed one of those 'High Flow Spun Diesel Cats' by Magnaflow in mine.. you can see right thru the thing ( Magnaflow # 60010)

 

I made my own we simply took it off and took a crow bar and a 5 lb hammer and removed the inside material. The emissions test for it is simply a visual check of wether or not it has one there is no way to tell if it works, and the factory ones barely did anything anyways. so gut it and it'll be free flowing and still pas the test by appearing to have one.

 

I like this idea... do you just use adapters to go from the 4" pipe to the 3.5" pipe?

 

I suggest a 2" paddle bit and pry bar. LOL

 

Yeah, you can can a adapter for pretty cheap. THey have a bunch at store.airflo.com

Just make sure you get the correct one, ID/OD etc.

 

Not exactly, see when I got my truck it had a Dp and a 4" exhaust, no cat or muffler. I modded it to a 6" exhaust right behind the DP out in front of the tire. My sate requires emissions testing so when I went to get my test the guy told me I needed a cat I told hmi my 99 doesnt have one and he never complained about that he said my 99 never had one from the factory but all 96's did and the state requires it still have one. I got it from a dealer and they are required by law to ensure it will pass emissions as part of their sale in colorado so they paid for a cat to be put on, I talked the guys at the muffler shop into knocking the guts out first, they had problems though as nobody has ever seen or haerd of a cat with a 6" inlet and outlet. so they took one with a 4" inlet and outlet, and cut 3" of 4" for each end and fitted it between the DP flange and the 6" bell with some custom welding.

 

similar thing happened to me.. truck had all straight pipe when I bought it.. got bagged for no cat (didnt know I had to have one) so new exhaust and new cat $$ and passed reinspect