Chainsaw Repair

I see people regularly increasing the displacement of their saws with bigger pistons and heads.   I see that some series use the same stroke and different bores. 

Is balance an issue on Stihl motors?  Does anyone measure the piston weight of aftermarket pistons as compared to stock when replacing?

I'd think that it would be important on a saw that's turning 12k+ rpm. 

I plan on tigging a small dome on an 025 piston.  I'm just wondering if I should relieve the sides under the skirts to keep the weigh the same or not.