In NSW the pod's are illegal, that's what Phill was getting at.
I am running full atmo, was running GFB but wanted a sound change so I got the HKS SSQ.
It went off anything from 1/2 throttle up which got irritating, so I bought a longer adjustment screw from Bunnings and put that in and tightened it. Now it really only "whistles" at full throttle which is a lot easier on the ear, and you can control it as such a lot better.
I have had no issues with idling, misfiring etc. Car runs fine.