Well I installed my new 4 inch Rineharts on Thursday and put about 500 miles on them in the last couple of days.First I will say they sound great but my first impression was they were not very loud.After putting some miles on them I decided they were loud enough but not to loud.I installed them on my completely stock 2010 Ultra Classic.One concern I had was how little of clearance there was to the axle nuts.I decided to play it safe and replaced the 1/2 inch bolts with 1 inch and then used 4 small lock washers on each one.By doing this it moved the mufflers a 1/2 inch away from the axle nuts and everything seems to be fine.I will contact Rinehart at the first of the week and see what they say.I rode with 3 of my buddies that have the standard size Rineharts and couldn't tell any noticeable difference in the sound.My buddies said they liked the look of the 4 inch and that they sounded really good from behind.Overall I'm happy with my choice which was between these and Vance & Hines.