You have to take a look at the type of riding you do the most then decide from there, if it is lower highway RPM's you are looking for and that is the majority of riding you do then you could look at something as simple as changing your drive pully for less rpm but will sacrifice in other areas, its a give and take game. AS for my bagger most of her time is spent around 70-80mph and she is just starting to crank up around 4k. Too many tickets and the crocked insurance companies that my tax dollars help feed of us keep my speeds to a min. at least most of the time
Here is a link to an accelerator calculator you can have some fun with guys,
http://www.nightrider.com/biketech/accel_sim.htm
Cheers,

 

A short-coming of the data on that link is that the torque figures are measured at the rear wheel, but corrected to crankshaft figures. The actual torque at the rear wheel is 'rear wheel torque' multiplied by the gear ratio. That correction is taken into account by the invisible calculations performed by the website, but is worth pointing out.

My S&S 107" gives peak torque of 107 ft lbs, however my bike started out life as an International spec model, with top gear of 2.94:1. With that original gearing, actual rear wheel torque would be 314, but with my current gearing, of stock US 3.37:1, it is 360. With 14% more torque, my bike with current gearing will plainly out accelerate it with its original gearing, when in the same gear.

 

When I twist the throttle on my bike, it goes......at highway speeds, it vibrates.......that's all..........