"Is there a downside to the o2 simm?" Not that I know of. I was just saying to wait so you wouldn't spend more $ if you didn't have too.

As far as the perf. of the CA cat compared to regular , I can"t say . I could only speculate there might be a small perf. hit , But, probably nothing to even think about.

My cat was bad and I did most of my mods within a day or two and some the same day. So I noticed a big perf. gain. I should have done one at a time just to see which gave the most perf.

 

Like HTM did in this thread, I'm trying to spec out a new exhaust system as well. Since I want to stay with a single system that's aggressive, but not too loud, I'm going with the Flowmaster 50 HD. My stock system has the normal dual in/single out cat (2 in. x 2.5 in.) currently, but I want to replace this with a new Magnaflow cat. Here's my question: Since the Flowmaster 50 HD has 3 inch in/out, should I go with the 2 in. x 3 in. cat (94047) or 2 in. x 2.5 in. cat (94037)? Would I see enough performance gain by going with a new 3 inch pipe between the cat and muffler to justify the expense? I'm about to drop big money with Summit, so I would like to know some opinions.

 

Dodge made a change in 2000. To beat the changes in the CAFE standards that were going into affect in the fall of 2000 for the 2001 model year Dodge put the 2001 models out in early 2000 to build as many as they could before the standards changed. In 7/2000 the next generations of the 2001 models began production which met the new CAFE standards. The computers are even different between the models. So when ordering these converters look under truck to make sure you have all the O2 sensors accounted for.