ok ... once again .. i know thiis a old thread ...
i am runnin a 15/40 with 20s on the back and i love it .. compared to the 13/40
my buddies warrior runs...mine smokes his now hes in 6th WOT(wide open throttle) and im maybe half thorttle it makes a really big difference, just depends on what u like ... as far as takin away from the bottom end , i dont really noctice any, thewarrior is geared so low anyway ... but this is all on stock machines... but i personally love it and considering moving to 16 ...