Holy crap what a dumb idea. If it doesn't work the penalty for that would be worse than being too noisy I'm sure.Do you have any buddies with a certification letter? Why not just photshop one and print one off yourself? Is a cop on the roadside really going to know the difference?
Any special stamp or embossing on the letter? Get a buddy to "lose" his certificate letter and get another one to replace and give you an original?
In Missouri it would amount to a forgery, which is a felony.