I worked for a chevrolet dealership in 2002 (when I bought my cavy) and I would like to say that ALL of the 2002 2.2L cavaliers make a popping sound from the exhaust.... All of them, not when your accelerating but when you let off of the gas (mostly at high rpms) Does it most of the time but not all of the time.....sometimes it will decelerate without popping. I bought a Jet Performance Control Module(when I was dumb) and it actually made the car "pop" less and all the module hooked to was the TPS sensor and the Map sensor. But don't buy the unit, its a waste of money....they "burn out" quick and will make your car start running funny. My car "pops" so bad now its unreal, I have a PS header - catco freeflow cat - ebay muffler all 2.5 inch piping......no resonator. I personally hate how it sounds but don't really care cause it makes race me.....

i have a 2.2 and before i port and polished and began to rebuild mine did the same thing, i dont know the exact cause but mine went away after the port and polish. usually a "pop" from the exhaust is a backpressure issue. maybe change the size of your cat or piping.

dude there is liek a 2-3 page thread about the poping noise in exhuast either on this page or a a page or so back

actually its 1/2 way down the page...