gearing

Wanting to know what a good gearing setup for highway riding, wanting lower rpms since I already have a loud exhuast. Current setup is 17, 40

Purchased a gen 2 this winter and just got it on the dyno the other day. The bike made 168hp @ 12,500rpm and 77 ft lbs @ 10,500rpm. Based on these numbers what's size sprockets do you guys feel like would be best? Street and strip bike 1/8th and 1/4 mile. Thanks in advance for any helpful info!