I just installed a series 80 flowmaster and am thinking about a resonator. What, exactly, is it and what does it do?

it makes the exhaust a little quieter, and you already have one on from the factory

Ah, ok then.

how do know that you have a resonator? i have a 97 se and i dont think i have one. when i rev it up, it pops as the revs fall back down.

remove it and you will see

Thats the best thing I've heard in a long time. Kudos!
Seriously, ElMacho, me thinks that only the 92/93'* (excluding the older body styles, obviously) were without resonators, so everything beyond that should have one.

Well, any tips on how to take it out without damaging everything

Don't do it. It'* not a restriction, and you won't be happy with the noise. I added one for that reason.

The resonator is the 'fatter' piece between the catalytic converter and the muffler.

Ok, got it now!

Willwren, could you share the part number and size for the maganflow resonator installed in your car? Thanks!