426 or crf450. I've ridden a fresh KTM300 dirtbike and power was unsatisfying to me on the bike. Add a couple pounds, lose a couple horses. Honda engine parts are dirt cheap compared to most other liquid cooled 4 stroke engines and the power stock is broad enough to carry the extra weight. Check out the walsh crf hybrid ltr that Cody Gibson rides. Saw it in person several times with a few different riders and it's very dominate out of the gate and smooth.