Well most would say go with the 3" catless. I have that on my 03 and it sounds good. And when I bought my cai used from a guy on craigslist it came with a pcm holder. Also with my new pcm it shifts at 6000 rpm now. That's the most I want to go. And as u buddies car goes I dunno. Some people say that they run no kr after a pulley swap. Could just be a freak car is all