Going down the path of hopping-up the KLR650, I think you find yourself suddenly in the Realm of Diminishing Returns.
A Versys engine, out-of-the-box (and a number of other 650 cc mills), will eclipse the performance of the most highly-modified KLR650 engine.
Yet, if the modification satisfies you, have at it!
The magnitudes of modification performance increases are seldom quantified, e.g., by dyno run or by competition. Their prowess often resides in the seat-of-the-pants meters of the modifiers, and in the head-space between the ears of the tuners.
Then, there's the PCV valve mod, which . . . oh, never mind!