Most of the gains are to be had from a muffler mod, like 20% more power, then another 10-20% from porting, and another 20% with some extreme mods. Ported it will run 1/4 .043 14" no problem, but it is a slow chain. Personally I'd stick with a 12" bar for 3/8 .043, and look to cut 10" max, but it...