Flywheels.
Fit a light weight flywheel to dramatically reduce the weight of your rotating assembly. Bang for buck, this is a great mod, and doesn't require you pulling the motor apart.
Use the link here to see what counterweight you need, and what the part number is:
http://www.racingbeat.com/RX7-1975-1985 ... 11436.html
Early rotary and RX7 S1/2 are still available for now.
S3 RX7 are very hard to get now. Used is your only option. I've sold mine.
S4 RX7 are available but second hand are hard to find in UK.
S5-8 RX7 are available easily new and used.
Early rotary up to S2 RX7 are 215mm clutch and associated flywheel.
S3 and S4/5 NA motors are 225mm clutch and associated flywheel.
S4-8 turbo flyweeel are 240mm (235mm units might as well be the same thing) clutch and associated flywheel.
You can get aluminium flywheels or steel units. Steel will be a bit more driveable on the street.
Used flywheels don't come up for sale in the UK very often. New units are available but not cheap.
Back in the UK for the summer, maybe longer......