My car runs a 3in dump and 200 cell cat and then tapers down to the stock 2/1/4 back section. It varies polo to polo but mine has the resonator as well as the muffler. I'm thinking i'll just go ahead and remove the muffler. The 2/1/4 back section looks to be mandrel bent so I think it'll flow plenty enough with the biggest restriction there being the muffler. I think that with turbo + cat + 2/1/4 rear pipe that the noise level will be fine, but thought I'd just see if anyone out there had done similar and if it was likely to be louder than say a non resonated 2/1/2 back section with a muffler as I've heard that even those can be pretty loud.