Are Rotary Works throttle bodies good for the Mazda RX-7 FD?

The source material doesn't directly evaluate Rotary Works throttle bodies, but it does establish that most FD builds don't need an aftermarket throttle body at all: the stock FD throttle body has been proven to comfortably handle around 550 horsepower, and it can support 800+ horsepower on a 13B engine (and over 1000 horsepower on a 20B) when running methanol fuel ¹. If you're considering a throttle body upgrade purely due to horsepower constraints, the stock unit is unlikely to be your bottleneck.