OK I noticed this the first time on the weekend I revved the car a little before leaving Kiama and I heard it backfire.
I noticed it again today, it did it a few times. I had come up a hill around the roundabout and it split to 3 lanes, I hammered it fairly hard in the far lane to get past all the other cars then pull back into the lanes merging back again down the hill before the next roundabout. So I changed down gear to slow down then also used the brakes as the roundabout was coming up fast. I heard it do short sharp little backfires, not hugely loud but they were still there.
The only thing Ive done recently is put the SRI on, everything else is stock and its also due for its next service in about 1000k.
What could be causing this ? Is it bad ?