What mod does every bike need, but is rarely done?
A loud horn. In 1980, I got a pair of Stebel horns for my GS1000. They use a lot of juice, so I had to put on new wiring and a relay. They were too big to fit in the stock location under the gas tank, so I mounted them on either side of the headlight. They face forward and are so freakin' loud they will almost shatter glass. Also a zillion times better than revving the exhaust.
Well I was riding on a street when I thought someone threw a can at me. It bounced off the bike and landed by the gutter. I pulled over ready to kick a$$. Then I noticed the can was one of my horns. After 27 years of vibration, the metal strap I used to mount the horn had snapped.
The first picture shows the snapped bracket on the right side. The second picture shows the left horn with a new bracket. You can admire the braided steel brake lines, but ignore the dirt and leaky valve cover gasket. Notice the horn faces down so rain water will drain out.