Haha yes they are pretty cheap. really regretting buying them now if that's what the problem is lol

 

Dude it's normal after you replaced your stock mufflers with higher flow ones with less sound deadening you started hearing what the mufflers were keeping quiet my 04ss dose the same thing prolly louder since I deleted the resonator and put magnaflows on it and I bet if you rev it in park you will hear the same sound when you let off and the revs fall off you are deffinatly hearing a cackle my f-150 that is straight piped dose the same thing, it's normal if you hear it when you are accelerating then you worry and if you want to hear a real back fire swap 2 plug wires (preferably on a beater) and start it the sound will be very different you will even hear it come out the intake and that my friend is a true backfire as in it is firing backwards

 

Reading all your replies...kinda sounds like this?
(skip to 3:40 for the first.then there is one while still & one running)

 

Mine makes this noise when taking advantage of my 2-step.

 

I did custom exhaust, on my 3400 monte, basically, when i let off the gas after being on it round 2000 rpm or so, it'll just give that rum rum pop pop pop noise, its straight piped with res delete as well. It sounds great, and i like the noise, hopefully i helped you point out that your not the only one But this is just pipes, no mufflers etc. the reason yours is making noise that might be unpleasant for you is because you bought those cheap mufflers sounding like a "ricer" hehe.

 

Hey have any of guys heard this “backfire” sound come from the engine bay?? I heard this now twice when starting the car I know it is under the hood cause the first time it happened I was under the hood when my boyfriend started it. I even saw that the sound was dead center of engine. Thank you all

 

To be classified as a backfire, it must come from the engine bay. Anything coming from the exhaust is technically an after fire.

I'd certainly look into it further, I've seen plastic intakes on 3800s blown to pieces from this.

 

Id check the fuel pressure regulator before you start it anymore.. As said above me, these intakes can blow up from a faulty FPR leaking gas into the upper intake manifold (plenum) and cause a real headache..

 

I'm by no means an expert, but heres a quick video I put together on the subject.

Link