Generally speaking, K&N Air Filters are an upgrade from most, if not all, Stock Air Filters. It doesn't seem likely that the popping on deceleration would be the result of the K&N Air Filters being installed on the bike. However, if everything else on your bike is 100% stock, perhaps those K&N Air Filters just might be the culprit. One thing I've come to understand about the M109R and bikes in general is...No two exact year models with the same exact performance components are going to run or perform exactly the same. Some of our 9s simply more sensitive or robust and rugged than others, and I don't think there's any rhyme or reason as to why that is. I had some practically brand new Stock Air Filters (changed them out within the first 100 miles on the bike) in my collection of extra OEM parts. But, I'm not sure if I still have them or not. I hope to be out in my garage this weekend installing my new BCS FULLY FLASHED ECU on one of my M109Rs. If so, I will try to locate those Stock Air Filters. If I'm able to find them, I will respond to this post, and let you know. You can have them free of charge. Just pay the shipping cost, and I'll get them shipped...if I can find them that is.