A sprocket like that would pretty much kill the top end, right? My old EX500 had a +4 in the back, it would be doing like 8K RPM at 60mph nfloor I changed it out to a +1 ASAP.
I know that's not what you bought the 929 for, though. Looks pretty trick. If I could buy a bike to just play with I'd definitely do something like that - it's gotta be fun off the line and for wheelies, fer sure - but I can't do that to my daily driver.