I just got a Maroon 94 (I believe) Blazer w/ a 4.3 engine. It can't pass emission and is limping badly. I'm gonna replace the cats and O2 sensors (should only have 2 right?). Are they are other critical emission parts that I should be aware of, if I don't pass emission? Also wondering if I should install OEM Cats, or are there performance cats availble for slightly more. I'm thinking of swapping out the muffler, but I'm not sure how it will sound. I've got a 94 Caprice w/ an LT1 engine, w/ 2 1/2" exhaust and Summit Turbo mufflers, it sounds great. I'm just concerned a 4.3 engine might sound "rice".

 

well idk about the emissions...but there are high flow cats that dont restrict exhaust as much.

 

id consider putting new plugs and wires in it also. could have a cut plug wire that could be causing the truck to run poorly. would also make you fail emissions as well