Ordered the Straight Shot and paired it with the Filter kit. Performed the Mtronic relearn and my 661 is a completely different saw. It is definitely louder, my parents could even hear he difference from 500 yards away on the other side of there property. The Power difference is not even comparable to stock, this saw just eats and powers through far better than before. Great hearing protection is a must, but if you can deal with that you wont be disappointed.