I would do the build myself. It's just nuts and bolts right?

Half serious, half kidding... But really can't be that hard to at least build the head. I've taken apart and reassembled B18 Honda and Jeep motors before. I can't imagine the 2GR being that complicated.
Is the TVS1900 the supercharger used on the Emira GT4? If so, pretty sure that just moves the powerband (at least with the current GT4 tune). I've never personally owned a supercharged vehicle. The linear powerband is strange to me coming from numerous turbo vehicles.