Tech'ish question. Inquiring minds want to know.

[scourge at cogeco.ca (Scourge)]

So I've been wondering. 

What makes a car backfire? Not regular loud single shot backfires, but the awsome little pop pop pop some cars have on heavy downshifting.
 My golf used to do it like mad, I loved it. Made it sound so raw and hardcore, lol. Non of my rocco's have ever done it.

One guy I know once told me it was cause by small holes farther up the exhaust(I guess he meant near the DP) that while leaking a bit would also create a sort of scavenging effect and pull some air back into the exhaust system. That air had oxygen in it and could then act as an accelerant with the bit of unburnt fuel and it would ignite in the exhaust, thus creating the "pop pop pop" when downshifting. I have no idea how accurate this is.

Any thoughts/input??

-George -missing crazy things my golf could do(like shoot flames out the tailpipe!)