There are HD rebuild kits but the A140E is not heavy duty. Doubt will find real HD upgrades as with some Chevy trans. The reason being the 5SFE and Camry is a commuter car mix and its engine is designed for commuter HP output. A healthy trans should be able to handle 200 hp.
Swapping a 5 speed has been done and a bolt on if you have all the parts.
One option for the MR2 was a turbo 3SFE called 3SGTE. The 3SFE was previous to the 5SFE design which was also used. Look at the MR2 owner sites as they were more inclined to modify your engine model.
Turbo of the 5SFE has been done, search the internet for photos and info. Ebay may have something on parts. It is just a function of time and money.
At one time the dealer below offered a turbo kit.
The 5SFE can throw a rod if over revved.