Bikemike go further with that muffler mod. Cut the stepped sectionnall the way out, right back up to the outlet.
You'll also want to advance the timing 8 degrees. Its around 1.1mm off the cast on key. I have done a truck load and they become very angry little saws!
Another gain is removing the saftey bumpers from the chain and increasing the top plate angle to around 33°. They still produce that silky like cut but you can spear and box cut like a 200t.
I love climbing with mine! So light that i thought i had dropped it of my harness the other day