Boy! I can't wait til I get paid next week :lol
http://www.hmfengineering.com/yfz450pg.html
http://www.hmfengineering.com/yfz450pg.html
If you add the removable quiet core insert you should have no problem with decibel testing.
Our spark arrestors are made to forestry specs but we have to submit some drawings and paperwork with a giant check to gain their stamp of approval. That should be clear in the next few months.
Joe/HMF