Your on the right track with this. I can't give you any dimensions, but I can tell you how I solved my problem. I removed all of the spacers.I then cut a hole in the OEM muffler end cap to enable the OEM cap to be mounted over top and cover the Supertrapp cover. The hole sawcut with a quality metal cutting blade is a must. You only get one cut so you have to think about this carefully. Make sure you use a punch to mark the center of the OEM end cap 'dome'. This may or may not be to your liking, but it worked for me. I've attached a photo so you can get an idea what the final result should look like. The rilly only down side to this is if done correctly (if your hole is big enough) the wording of the Supertrapp 'off road only' shows a little as you can barely see in the photo. I hope this helps you out. Good luck. The sound of this Nightstick/Supertrapp mod is, as he said "Awesome".