I am curious to which tooth count people chose and how they like it. I'm looking to maybe go -1 +3 or +4. Just want to see what others have done, their personal opinions and the pro's/con's of it with these bikes.
I've got 15/45 on my 2005 600 track bike. It works for now, but I'm going to try some other gearing combos next season. I'm hitting the rev limiter in 4th gear about 100' before my braking zone at my favorite track. First thing I'm going to try is a 180/60 tire and if that doesn't carry me further down the straight then I'll look at different sprockets.
A friend of mine has an 05 750 track bike with 16/45 gearing and he loves it.
On a street-ridden bike, I never fucked with the gearing. The minor improvement in acceleration was never worth the decrease in fuel mileage and added noise levels. If your chain and sprockets are in good shape, try a -1 front and see if you like it. If you need to replace the whole set, I think -1/+2 is the most aggressive gearing I'd consider.