PIONEER +1mm STROKER VERSION, with optional ceramic bearings  NOW COMES WITH A HARD CHROME OWNER REPLACEABLE SLEEVE.  An Optional welded crankshaft to help prevent crank twisting is a $45 upgrade.

You can get either the 26 or the 29 Pioneer with a +1mm stroker crank now, that makes them 27 cc or 29.5 cc.  Either engine will rev about 1000 RPM higher with the stroker and because of this they come with slotted big end connecting rods for better lubrication and cooling of the big end of the rod.  The stroker option adds $120 to each engine. 
 
The next option is the 4 ceramic main bearings with plastic ball retainers which gives a little more power at the top RPM but the most important thing they do is they get rid of the steel ball retainers of the stock bearings.  The stock steel ball retainers will occasionally break from the high RPM, this does quite a bit of damage when the metal comes out in the engine.  The 4 ceramic bearings add $85 each engine.

See below for dyno graph and photo of slotted rod crank.