A friend with a 150 took off the muffler, added a silicone straight pipe, and VP20 oscillating pump and got another 1000 rpm. I did the same with a 100 and only got another 400. But it was much harder to hand prime and start so I put the muffler back on.

Hey Bill, whats a valve gear? Is that something I can see after removing the valve cover?

My 100 is my first 4-stroke and only my 3rd engine. It was very easy to tune and it flip starts by the 3rd try every time. I love it!

Clark