There have been several posts about the Ness Big Honkers on this site. You might want to consider doing a site search to get the latest info. I have Big Honkers on my Vision and the heat shields fit perfectly. WhileI can'tmake much of a comment about a performance improvement with the Big Honkers (I'vedonea number of other performance enhancements besides exhaust) the Honkerssoundmuch, MUCHbetter than the L1's or L2's. In fact, there is NO comparision in terms of sound quality, intensity or volume. The Big Honkers just sound GOODwithout beingtoo loud. In fact, several of my HD riding friends have mentioned how good they sound. I found that I had to break them "in" for 300-400 hundred miles before they came into their own. Hope thatthis comments help you make a decision!