I've got the Sumo on my Brocock Bantam HiLite. It reduced the report 12 decibles...from 72.9 db to 61 db. It's so quiet that I don't hear anything coming out the end of the barrel, just the hammer and valve opening. They're pretty amazing. Not to mention the owner is one of the nicest guys you'll ever meet, he definitely takes care of his customers. 

 
I have two Sumos, very effective. Here's an example of his customer service beyond the almost instantaneous email replies. I bought and then returned an adapter that didn't work for me.Fedex lost it . Donny PayPal' d me the amount immediately when I asked if he had received a damaged package that couldn't be tracked, even though he had not seen or received it. Wasn't high finance ,after screwing with Fedex for a month I finally got to give him the amount back courtesy of Fedex. That's just how he rolls. Tom
 
DonnyFL has excellent customer service and his moderators are top notch. He has thrown in free items in my orders which I would've happily paid for. Genuine guy. Between 2 rifles (Daystate Huntsman Regal .22 and Brocock Contour S6 Elite in .22), I have 3 of his moderators that I switch between. Fat Boy, Sumo, Koi, and I have a 4th one on the way. The Tanto. I'm addicted to his products. They're a piece of art. I purchased all of his moderators in the .25cal version even though I only own .22cal rifles. I'm working on saving up for a .25cal bullpup or rifle so I could use them between the two calibers. 
 
I already replied up above but was just thinking... he also replied to my e-mail's immediately, even at 10:30pm. He gave me a 10% off coupon for my moderator for no reason - just to be cool and he shipped my Sumo immediately. I don't think I've ever seen anything bad said about him or his products. If everyone ran their businesses like DonnyFL there would be a lot more successful businesses around! He's great in every sense of the word and so are his products. BUY ONE!!!
 
I would also like to add to my earlier post. The first time I ordered one of his products (Fat Boy), he made the process easy. Before his new website was up, there wasn't a shipping option to select in the drop down menu for Guam. He walked me through the process via email and using PayPal for the transaction. He answered all my questions in a timely manner. But with his new website, I no longer have to use PayPal and the process of ordering is quicker with my card on file. Could be dangerous though because I have ordered 3 moderators from him in the last couple months. No self control on my part lol.