SFOB M/T questions

Posting here due to account not being old enough for the "tuning" section .

So , I pulled the stock muffler off my 22 Pro M/T and put in a Resonator. Definitely makes listening to the truck easier . The 1st thing I noticed was after cold starting, I get an initial growly, mean sounding exhaust note . Ya know... the kind that sounds like there's some power there . After a few seconds the growl disappears and changes to a purr at best . Just like my 6.0 Power Stroke cold starting before the VGT closes and blocks half the exhaust housing if any yall are familiar with that .
So is what I'm hearing the motor switching to " Atkinson " mode and I'm hearing the loss of compression ? Also , when I decel/ downshift it will growl and crackle just a little ( maybe for a second , or two tops ) and then go quiet and purr its way down . I can however make it crackle and get that growl back if I ever So slightly keep my foot on the gas , but again just for a second . I'm KD Tuned also .
My other question is , I just read something about the VF " Super Full OTTO Base " tune implying it virtually eliminates the Atkinson cycle . Is this true , and for those running that tune , did it change your exhaust note ?
Is the SFOB tune louder ? Am I on track with any of this at all ? Everything I own is tuned & hopped up so I'm really after that aggressive sound . Sorry for the long post , I really did do countless hours of reading the tuning threads here and multiple other sites , but couldn't find any info on what I'm trying to learn . Thanks for hangin in through all this .