All my previous Tiv's have provided that lovely pop bang on the overun, thus far my recently purchased 4.3 Griff seems reluctant in this department. It's certainly up there with the exhaust note and noise just no pop bang??
Was the exhaust hot enough? If you take you foot all the way off the accelerator then fuel is cut completely until tick-over is achieved. Leave your foot slightly depressing the accelerator and you should find plenty of unburned fuel popping away in that red hot exhaust.
I must say that I've not managed to reach satisfaction on this front yet either. Should they all do it? How long do you reckon it should take to heat the exhaust sufficiently?
It really bangs if you have the pre-cats removed and the silencer modified, but you do need to keep a small amount of throttle open on the cat RV8's to keep the fuel going in. Mine does it from cold!!