Sure, you could turbo the RX-8 to beat the other cars, but you could turbo the other cars and beat the turbo RX-8.
Putting a turbo on a car goes farther than just slapping the turbo on and expecting big numbers. You have to pay attention to A/F ratios, spark timing, compression ratios, boost pressure, and detonation, which can destroy your motor if you aren't careful. If the stock internals can't take as much power as your trying to get, parts from inside the motor may end up outside.
The point is, you can do anything with any car if you have the money and knowledge.