OK so my downpipe and flexpipe are looking pretty rough.. so I was thinking of replacing just the downpipe system, however, I read up on some forums that you can install a 3.0 downpipe over the stock 2.25 to get better performance and better turbo spool. So my question is, is this true and will this work without doing a cat back system? I plan on just installing the downpipe and using the same exhaust system and muffler that's on it now. TIA

 

I don't see the downside assuming your flanges line up and you don't have an exhaust leak - worst case is you do the downpipe first then decide whether to do the cat back later. Note some people have had issues with CELs following and have resorted to using CEL-Boss type O2 sensor spacers on the rear sensor.