Unlike the front brace on the MR2 Spyder where the trim had to be cut and the spare tire lid removed, the TRD rear strut tower brace requires no modifications. In fact, a 14mm wrench and about ten minutes is all it takes to replace the factory x-brace with TRD triangulated unit.
The procedure for this install could be summed up in one sentence, “unbolt the x-brace and install the TRD brace in its place.” But more specifically, remove the 3 nuts from the top of each strut tower. Then remove the 2 bolts at the top of the x-brace where it mates to the firewall. (If any of the hardware seems stuck, just pick your poison. Hit the wrench with a mallet to loosen them or use a breaker bar.) Now remove the x-brace and install the TRD bar in its place. Optionally, you can remove the metal ring at the top of each strut tower as the base of the new TRD unit serves the same purpose as these pieces. However, the bar mounts and works the same with or without the factory rings.
Remove the nuts and bolts (highlighted) and then pull the x-brace out of the engine bay.
Once the x-brace is removed the engine bay will look like this. Keep or remove the metal rings from the top of the strut towers. The bar works fine either way.
The TRD strut bar installs in the same place as the factory x-brace with the addition of a strut to strut brace. This piece is also a lot more substantial.