I agree with swjohnsey on this one. Going down two in front and up one on the rear is a huge change. Personally I think you'll be sick of it in an hour or so. The most popular change is down one in front, and even this is pretty significant. I usually recommend going up on the rear only, one or maybe two teeth. This may get you into trouble with the chain's length, but it avoids a potential problem with the chain riding more severely over the front of the swingarm guide. This wastes some power, wears out the guide more quickly, and can make proper chain adjustment more difficult.
Lowering the drive ratio is something else that is often miss-understood. Everyone talks about greater torque and acceleration, but in some ways all you’re doing is covering less ground more quickly. It’s much like peddling your 10-speed in the lowest gears, your peddling like crazy but going no place in a hurry. It certainly does 'feel' much quicker, but you may actually be worse off in all but a few situations.