I recently installed the DX Pipe and 2" cores on my 13 SEUC. Was thinking about the 1.75's but Doc at Doc's Performance Tuning recommended the 2". My concern was that they would be too loud, I had 1.75" cores on my '07 and it was louder than I expected. Turns out the packing had wadded up at the end of the muffler and was burning away, hence getting louder. We used the screens that Fullsac supplies and put all the packing back in. Nice mellow rumble, even tone at cruising speed with a nice bark when you get on it. I had Doc do the tune so I can't speak for the maps Fullsac supplies personally but would have gone that route had I not had the opportunity to have Doc work his magic on my engine. I would recommend Fullsac products with or without a discount and would highly recommend Doc for a precise tune, I've never ridden a better, smoother running Harley, didn't seem like the same bike I rode down there on.