Been tinkering with the S-40 and have fit a National 'StreetShield EX', and a Marauder headlight.
The screen was a challenge because there is not enough room on the flat handlebar for the clamps--the master cylinder is the issue. I ended up using the risers as attachment points. The riser bars are slightly larger in diameter than the 1" handlebar, so the clamps had to be enlarged with a Dremel and sanding drum. It was a little tedious, but got the job done.
The Suz Marauder headlight is a simple bolt-on mod. If this is something you'd like to do, find one at a wrecking yard because they are not cheap from Suzuki. The shell is larger diameter than the Savage/S40 unit and has a halogen bulb which throws a lot of light onto the road at night.
pics:
http://tinyurl.com/4kr8d