808 mod, socket for op-amp to try several (forget what one is in it), replaced the signal path caps with WIMA's.
Been a while since I did it so maybe some other stuff. There's a web page on the technology of the TS which I read and followed.
The guts of the TS-5 are the same as the TS-9, just in a plastic housing. I figured I'd try stuff out on the super cheapie in case I wrecked it. Turned out so well that I just use it.
If you want to mess around, pick up a TS-5, they're dirt cheap.