Couldn't read thru the whole page ... actually was kinda annoying
Flames, Popping sounds, whatever you wanna call it is the fact that 02 is being introduced with fuel and hot exhaust in your exhaust system thus causing that Flame.
*cough* 02=oxygen *cough*
So it's normal when your downshifting cause of pushing air out u cause a vacuum and suck air back into the tail pipe