Nice looking Wiseco piston. I see they also offer it in a 2mm overbore.

Edit: I see L.A. Sleeve offers sleeve installation and wiseco pistons for our electrofusion KLX cylinders. Anyone ever research whole kit pricing on this route?

Edit Again: After looking through 12 pages of dirt bike sleeves, there is no KLX250/300 sleeve...so scratch that.

 

FWIW I noticed what seemed like a minor drop in absolute peak power with the bigger bore on my 650. It delivered max power at a lower rpm. Thing is with a big bore you tend to take advantage of what it does - increase low and mid range over stock bore - shifting sooner and lugging a bit more. So if there is any loss the only time it would really be noticeable would be in top gear max revs or if trying to over rev a lower gear to avoid shifting. And that was with a 27cc increase versus the roughly 50cc in consideration.

In short, the benefits outweigh any disadvantages.