Jason
I was led to believe that the level was 95dBA as I have a friend who has a modified vehicle and he sticks to the letter of the law (as we all do).
He also was engineered in the mid 90's.
It now appears that if you take a car in for engineering or registration that it must be 90dBA for builds/manufactured back to November 1983 construction.
Guess no problems if you were previously registered at 95dBA under EPA Schedule 1 that was revoked and replaced on the 1st of February 2003..
Starting to make sense as they (EPA) are making it harder by lowering the dBA level. Hell I'm happy with 95dBA.
Bernie