two down on the rear is going to give you less torque dude It will also increase ur top end
What you want to do is go up two on the rear. judging by what I've seen with the lack of low rpm torque the r1 has, you should see a good improvement. as far as top speed goes.....even on '02's you don't lose much
Yeah, what he said...however one advantage would be less RPMs at any given speed, so while cruisin at your 120mph ud be getting better gasmilage and putting less wear on the engine (Negligible). However, im pretty sure u wanted to go 2 UP in the rear instead...Hey u could try dropping 1 in the front.
two up in the rear (not two down). i recommend afam. you will lose some top end speed (but unless you ride at 160 plus mph on a regular basis, you will never notice). i went two up in the rear on my bike and was pleased with the results. also consider that going two up in the rear will throw off your speedo and mileage. you'll need a yellow box to readjust the speedo and mileage (less than $100 from what i can recall and fairly easy to install).
it's better to go 1 down in the front, because if you increase the sproket size, you either have to add a link or shorten the wheel base, which makes the front come up easier in heavy wristy twisty. you can get relatively better acceleration without worrying about the front end coming up when you go 1 down in the front (and subsequently move the back wheel back some to take up the resulting chain slack) as opposed to 2 up in the rear. just my opinion.