Originally Posted by Flatlander
I remember reading that GM set the speed limiter in the ecm according to the tire option on the car at the time of manufacture. If your factory tire option was H then your speed limiter was set accordingly and if your tire option was Z it was set higher even though it could be the same car otherwise. I'll have to check it out because my ssei came with the Z option tire pkg from the factory.
Correct up to a point. The highest speed limiter setting available was 128. Even though my 93 came with Z rated tires, it still got the 128 limiter that SSEi'* got with H rated tires.
The L27'* and L36'* got a limit of 108 regardless of tire speed rating.