What's amazing to me is that it's been over a decade yet the TurboExpress puts many GBA games to shame (unless you count portability/battery life....I never minded using an AC adapter). you can even watch cable with the coax input on the TV tuner!
as for weight, without the six batteries it was about as hefty as an original GBA (quite impressive since it was a portable console!). even with the batteries in it was lighter than a Lynx.
btw...
the original Street Fighter (Ken, Ryu vs. Hawk, Sagat, etc.) was the TG-CD game you're thinking of, Lstorm, although it was renamed "Fighting Street" in the US.
Street Fighter 2 was released on a Hu card, an amazing feat hardware wise at the time (had to be special ordered from Japan)...it was quite expensive then and goes for a small fortune nowadays.
The Turbo Booster was the device that plugged into the back of the TG16. It didn't improve the graphics per se, but it let you hook up the Turbografx console via RCA cables. This of course allowed for an improved video signal over RF, as well as stereo sound in games that supported it. A "plus" version of the booster was marketed near the system's demise that allowed you to save ROM data for reloading of your game (however, it didn't always work and the battery had to be recharded every two weeks). The TG-CD and Turbo Duo included both of these options, btw.