i get a lot of Backfires/rumbles/pops between 3500-4000 rpm during deceleration, I used to think it was normal until recently where it has gotten significantly louder and frequent.

I just changed my spark plugs and added some fuel injector cleaner. other than that, my engine is pretty much in good working order...or at least i think it is.

what do u guys think?

 

Do you have an aftermarket exhaust?

 

yes, a DC 4-1, stock cat, Apex-i resonator/b-pipe, mandrel bent axle back to an old school pre dynomax ultra flow (7 years old)

 

it's normal when you let off the throttle but you could be running very rich if you're getting pops on acceleration. Did you check what your spark plugs look like? black = rich, brown = ok, no discoloration = lean.