wonder if it is the GOV-MOD?
It is missing the littlest spring in the pic, but the biggest spring on the left is the main spring. Put 1/4" of washers in it and let it rip. If you shim the other springs you will have driveability issues. If you shim/eliminate the intermediate spring it will have dead spots in the middle RPM ranges and have weird pedal feel on hills. JUST SHIM THE MAIN SPRING AND BE HAPPY . Good luck.
Main spring is the high RPM cutoff, if you're trying to raise your fueling cutoff it's the one you want to shim (or even better find a stiffer spring!!)Intermediate spring makes the car driveable. Without it you'll have a REALLY hard time driving the car. Its total movement is practically nothing compared to the main spring too so it really isn't "limiting" anything.During normal driving the Intermediate spring is what is controlling the car - you NEED it to though.