These silicone rubber caps are soft enough to fit over most keys, but also won't fall off like fuel line (what I used to use). They keep the tree of the bike from getting all scuffed as well as paint on other bikes (like the Griso)
McMaster Carr part # 92805K11
There are other types of helmet locks out there, but there are none better than free. Attending a golf outing where the event was giving away a bucket of these cable gun locks. Many of the counties in Michigan give them away for free at the police station. They are strong and rubber covered. Lock the helmet to the bar (with hand guards or behind the brake master cyl). Will also fit through the D-ring.
Many NTX owners taller than 5'0" suffer with windshield issues. Some buy replacements or use add on devices. I like the adjustable type like the Wunderlich deflector HERE
It works great at reducing wind noise while still being able to see above the screen.
The NTX seat is one of the best stock seats made...ever. There is always some room for improvement on long rides burning that 8+ gallon gas tank. The quick and easy option is the Airhawk seat pad. Putting just enough air in it to keep pressure points to a minimum can double your ride time (it did on my FJR). The pads shown here are the small cruiser and Pillion pad. A new version called the 'R' looks like it may be an even better fit for the NTX HERE