I'm interested to see your DB numbers. I have a 22/45 with the Tac-Sol upper. I have used a Sparrow and also a Gemtech Outback II on it. Just from my ears I notice a bigger first round pop from the Sparrow but it then gets quiter than the Outback. Sparrow is an origional style aluminum core model.
The gun I find from strictly a listening stand point that is the quietest for me is my GSG with both the Sparrow and Gemtech. I would really like to see some numbers on the GSG since most tests have not used this gun.
If we weren't all crazy, we would go insane...