If you haven't removed the limiters yet, Take them off & throw them, Also take the baffle plate out of the muffler (be sure & loctite or HT silicone it when you put it back together) then you should be able to tune it. I have 1 - .455, 3 - .46s & 2 - .61s & they all run great. One more thing - make sure the pressure fitting in the muffler isn't plugged with something( I had that happen on mine once). Never mind the baffle part I just saw where you took it out.