Toyota MR2 Spyder Guide
2000 - 2007
Use the RaceCapture with the Legacy OBDII option, and de-pin pins 6 and 14 from the vehicle's OBDII port.
How-to video: https://www.youtube.com/watch?v=8CKnJlB5g8A
After de-pinning, you can insulate the ends of the pins with electrical tape and tuck them into the OEM harness.
Once this modification is made, you can configure the OBDII channels as normal.
Explanation
The Legacy adapter works by translating CAN bus OBDII queries into "legacy" (pre-2008) OBDII queries, and back again. The effect is RaceCapture thinks it's talking to a modern CAN OBDII vehicle, albeit at a slower data rate.
This works fine for virtually all pre-2008 vehicles, because they don't have the CAN bus pins populated at the OBDII port, because... they don't support CAN bus.
However the MR2 Spyder does have a limited form of CAN bus present. When RaceCapture sends a OBDII query to the legacy adapter on CAN bus, the car receives those queries and doesn't know how to process it, which will cause issues with the instrument cluster.
The best solution is to de-pin the wires from the OBDII port (pin 6 and 14) so the ECU will not receive confusing CAN bus messages from RaceCapture.