[Kurlon]

I'd say your friend has spent too much time thinking and not enough time researching. : )

Nice theory, I've got dyno and seat of the pants data that says my Leo's helped my ST across the board, even at partial throttle.

Wing this past him... If a pipe change isn't affecting how the motor breathes at partial throttle, why does it need different fueling for partial throttle operation after a pipe swap? If you have to change jetting, you've altered something fairly significantly, just look at any Power Commander map from a bike with nothing more than a pipe change. All those non-zero numbers for low rpm, low throttle opening areas (aka the 'driving range') are changes in fueling from the stock 'zero map' included in the PC's firmware for operating a stock bike.