The MR2 Turbo suffers from poor placement of the stock intercooler. The intercooler is fed by the passenger side air scoop, which limits airflow through the intercooler. This means that the intercooler is not going to be as efficient as a front-mount design. There are several options to upgrade the intercooler. The first and cheapest is to disconnect the intercooler fan temperature sensor on the engine lid. By disconnecting the sensor the intercooler fan goes into a fail-safe always-running mode. This will increase the time the intercooler takes to heat soak, however the stock fan does not pull enough air through the intercooler to prevent this condition.
Your next option is to upgrade the intercooler fan with one from an aftermarket company, such as SPAL. Using a 7.5" puller fan is place of the stock fan, power levels will remain more consistent over a wider temperature range. This setup is even better when a pusher fan is installed on the opposite side of the intercooler. With this pusher-puller fan setup sandwiching the intercooler, higher boost levels are better supported over a wide ambient temperature range. SPAL fans typically run $65 a fan.
Your next option is to install an aftermarket intercooler with a bigger core. Oversized intercoolers are available from Greddy, HKS, and several other companies. Fans should still be utilized to maximize performance.