As other have said, the ported BOSS is very loud. The CR version on the other hand, isn't, but it does allow you to tune to rifle to the load, rather than the load to the rifle. If my experience is anything to go by it works very well. I have one on a .30/06 Stainless Stalker, and with very little work to find the "sweet spot" that rifle will consistently put 5 rounds into one ragged hole at 100 yards. Browning also published suggestions for the sweet spot with different loads, as a starting point.
