I have an 08 Ultra. The mufflers are true duels with stock muffler with a label saying use on 1584 - 1688 cc motors. i got 2 slip on mufflers label saying use on 1340 - 1440 cc motor. I took the 1340 - 1440 cc muffler and cut the rear baffle center plate out with a 1 inch hole saw. I drilled 4- 3/8'' holes in the front baffle. I put his modified muffler on my bike and it sounds real good. It has a real nice growl when I crack the throttle. Here's my question. By removing the rear center plate baffle and drilling 4- 3/8 inch holes in the front baffle of the muffler did I do enough to insure good exhaust flow with minimal back pressure? She rode real nice. I did not notice anything trying to slow her down. With summer coming I don't want it to run hotter than normal. What else can I check?