I've had Scarlett for a month and caught the mod bug bad... one of the first things I added was a HealTech GIPro DS-series gear indicator from Blue Monkey Motorsports
Install was a snap, the hardest part was pulling the fairing to run the wire. The most beautiful thing about this is it just plugs into the OBD plug under the seat, no cuts, no splices, just plug it in and program it using a stand or by taking it for a ride. The one thing I don't like is that because Honda's don't have a gear position sensor, the display only shows the gear while in gear. If the clutch is engaged it doesn't work. I can live with that though since I am no longer searching for the elusive "7th gear"...
It also comes in a couple different colors, I went with blue since it most closely matches the instrument cluster. It's mostly readable in bright sunlight, if I have my helmet's sun visor down and look through that it helps a lot.
All-in-all, I am really happy I added this. I don't see myself always needing it, but it's really nice as a new rider learning the bike. And if I ever want to remove it or if I sell the bike, no harm no foul!