cj_rumley and Hoss if I understand your post correctly, the AMA did publish engine noise standards but it was in the form of a handbook or recommendations to Clubs?

I'm even more perplexed then. Reading the article that is nearly 20 years old and thinking back... I was nothing more than your standard AMA member with no access to information beyond what was mailed to every member. So I surely would have thought the numbers I quoted would have been part of general AMA membership info???

So guess I’ll put this down as one of those things in life that I can’t explain why I did what I did and rewrite the article without the reference to the AMA.