I beleive I had the same exhaust set up as you. I had the V&H true duals and the SE slash down mufflers. I had engine work done and was the told that the exhaust I had would really hurt the performance. The dyno run with that set up I was at 82 hp. I changed the exhaust and nothing else and the hp went up to 102hp.The new exhaust was a D&D fat cat 2 into 1.