Heya,
I just got a used 2007 RX8 with 5k miles on it and when I rev the engine the rear end makes a few thumps which to me looks like it might be the exhuast. Anyone know what this is exactly or if i should get it checked out?

 

You mean it pops when you let off the gas?

I believe the heat from the exhaust is igniting the unburnt fuel.
If you have a catless midpipe you can shoot flames when it pops

 

I don't under stand what is wrong with your car please elaborate because your description was half assed at best.

 

Let the mother-in-law out of the trunk.

 

Casedogg got it right. apparently it is very common. its only doing it when im idle sitting at a stop and revving it high. we cant hear it when driving and I rev high so all is good i think.

 

Welcome to the club and please read the stickies.