The setup and plumbing for a twin turbo would be MUCH more complicated than a supercharger. Even though the hp is "free" on a turbo, since it doesn't need a belt like a s/c does, the power is always on with a s/c, not so with a turbo. There are ways around turbo lag, like smaller plumbing, smaller turbos, etc., but that'll compromise something along the power curve (i.e. less at top end). You can "tune" a s/c pretty easily as well, just change the size of the pulley. Either application will involve more changes and tuning to the engine though (i.e. bigger injectors, higher fuel pressure, different mapping, etc). Sounds like you want to give more hp to your daily driver, as such, I'd go with a supercharger. They're probably less expensive and less complicated to install than a twin turbo. One of those turbo setups that is at the back of the exhaust system might work, if you want a few more inexpensive hp's from a turbo system. However, because the turbo is located so far away from the engine, I'd imagine there be a significant loss of potential hp, as opposed to having the turbos located right next to the block.