Cat back problem

I've been searching the forums for anyone else have a problem like mine but i was unable to find it. Sorry if it has been addressed before. I have a 1989 240sx stock ka24e except injen short ram with a Tanabe Super Medalion Cat-back exhaust with 80mm piping installed about 2 months ago. At first it was making this popping noise when i was missing a nut connecting the exhaust to the catalytic converter. I got 2 new nuts and installed those snug. It was still making this popping noise so then i changed the spark plugs. After that it was still making the popping noise. This noise would come on wen i shift gears at around 3500 + rpms and during deceleration while i'm in gear it sounds like its making popcorn. When i'm idle and i tap the gas a little to get it to around 1100 rpms it pops a little also. Is it supposed to be like this or is there anything else i should do? Any response would be greatly apreciated thank you.

maybe it is the back pressure....that is what it seems like.

its called "backfire". its normal.

Yup, like they said. Backfire... it's just excess fuel-air mixture combusting in your exhaust system creating a "popping" noise.

yeah my N1 does that no big deal

yea like they all said backfire. i was freaking out when i heard it but now i dont. its fun sometimes. i need 2 get an exhaust mine is a welded on one dual tip i need 2 get atleast one of those fake ones for awhile that cost like $50 almost close 2 getting a n1 but not there yet.