The MR2 Turbo utilizes a distributor based ignition system. The ignition typically produces enough spark energy to handle increased boost, up to 17psi, depending on the car’s tuning.
The distributor cap and rotor should be replaced ever other year or so, depending on mileage and use. The stock cap utilizes aluminum contact points, which are not incredibly conductive. Marc Summer’s produces a high quality distributor cap with copper contacts. The copper contacts should improve the spark energy reaching the spark plugs. You can reach Marc at firstname.lastname@example.org.
Spark plug wires tend to be fine for most owners, although Magnecore and Nology wires are often used with success. TRD plug wires are also fine.
Many owners use aftermarket ignitions systems from MSD and Jacob’s, although only some users find that the Jacob’s system improves the car’s performance.
Many different spark plugs have been used by owners, and many find that copper, rather than the stock platinum are the way to go for the performance-minded driver. Note that copper wears out faster than platinum, but is more conductive. NGK BKR7E (5020) spark plugs are used by many owners, but can be hard to find.