G'day ' I have a OS 55 AXand also have on the way a 50 sx , not sure what would be the best engine to put a tuned pipe on ?</p>

Hi, you can get about 1000 rpm more with a tuned pipe.
I put a Rossi type tuned pipe in my OS .55 AX.'

Cheers.

'Tuned' mufflers another option? http://www.jettengineering.com/

Does 1000 rpm really make that much difference in the air ?

Sure it does, that represents a significant power increase. But remember you also get more linear throttle response from a muffled engine and no setup issues. So if you have all the power you need or want with a muffler, then stick with it. But if you want to try out a tuned pipe setup, then go for it. The Jettstream mufflers are a nice compromise, not as much power boost as a full pipe, and less hassle.

Cheer's

Jett

for sure, 1000 rpm makes a difference between a good take off and a not so good one, ask me how i know this.