So my part-time boss, full-time friend lent me his JDM DC2 Type-R weighted shift knob for the weekend. I had tried an imitation one (i.e. fake) that did not weight as much for a day, and did not feel much difference. But even with my casual, light, commuter shifts, I could feel a difference as soon as I screwed on the heavier OEM weighted shift knob in my Honda Fit.
I have to be honest, it wasn't night and day, but it was noticeable enough. The shifter just clicked into the next notch with my guidance. I tried a few harder shifts and it felt much better than stock. The weighted knob made it feel much more solid.
I like it. And now that A&J has come out with their own very reasonably priced short shift lever for the Honda Fit under their T1R line, I think I might have to look into getting the short shift lever with a nicely weighted shift knob. Maybe not a DC2 Type-R one though, it does get hot under the sun.