The cannon style varex i seen on another members car on here is basicly a strait pipe inside, with a hole before and after the flap that the gasses will pass through when the valve is closed.Mine works like a resonator when open, the walls are definitely not straight pipe.
I had a normal Xforce cannon for about 6 months before I swapped it for the Varex (cannon). To be honest, with the valve open the Varex sounds exactly the same as the old cannon did. Definitely no louder.
Yours must be different to mine. I've had mine about 1.5 years, when did you get yours?
When o[pen its a strait pipe, maybe the have changes the design?