Probably a stupid question but how can i get my exhaust to pop?

[Auditude2.0T]

I like the way the RS4 and even some other cars pop when they shift or slow down. I just bought a DP hope that helps but does it have to do with running lean or rich? Sorry for this dumb question but im just curious.

[Phrost]

I have APR93 stage 2 with just a test pipe, and I can get a good backfire once in a while if I floor it in 2nd gear and quick let off (at random RPM).

When I had a dump tube on my chipped (that's it) 1.8t TT, it would always backfire if I revved it a little past 6,000rpm in 1st or 2nd gear.