1986 - Toyota launches "T" - Bar (T-Top) roof option with detachable glass panels. Modified the front spoiler making it less boxy and more aerodynamic. The Supercharged version introduced in Japan.
1988 - The supercharged MR2 becomes available in North America. You can tell an MR2 is supercharged if it has a decal on the back left that says "Supercharged". A decal is on both doors as well. If the vents on the engine compartment are raised up (rather than being flat) it's supercharged. There is an LED light on the tachometer that indicates when the supercharger is being used. T-Tops are standard on the supercharged model with color coded mirrors (the NAs have black mirrors.)
http://members.tripod.com/celsmr2/History_MR2.htm
that might help a little...