Just installed a 13.1 head on my 2013 600 pro and it runs much better.
The clutch setup I had was about 100 rpms lower than what I liked
While running at 5000 ft. Installed the head and now it's spot on.
I'm Now running the same setup I ran last year from sea level to 3000 ft, at 5000 ft this year it pulls hard. For a 600. 8,300 rpm is the sweet spot for the 600 motor.
Good job, Brad
Glad your liking the pa head, I sure like mine and for a 600 runs great. I ended up changing my Carl's helix to the 62/38 position, 140/330 Polaris spring, and 58 gram BB weights I am seeing 8250-8300 at 9000ft and I weigh 230 with gear. if I weighed 40lbs less I could probably pull the 64/40 angle. what a great sled