The only things I've seen that sound good are the hot air mod (details here somewhere), and one I found on the web about replacing mirrors with small CCD cameras.
"Why waste your money on those types of mods for this type of car?"
Perhaps because some of us enjoy driving that way?
Face it, Insight or no Insight, I'm always going to be going faster than most people most of the time. I'm just glad that I can get 68-73 MPG (winter & summer) while I'm doing it