I've done the 16, 17, and 18, and yes I can feel the difference in off the line acceleration, and everything up to 4th gear. Like I said to Adey, it's only $20 + shipping from Brent....cheap mod to try. If you do most of your riding around town, or a heavy populated country like England, I'd recommend it. But if you do a lot of freeway riding, you'll probably want to stick with a 17 or 18. If you do a big bore kit and carbs, you won't need a 16 tooth unless you want to get the front wheel off the ground.
