The JB4 for the G70 is the exact same as the one for the Stinger, since the G70 is using the exact same engines that the Stinger uses.
In the 9 months and 10k miles I've had a JB4 on my Stinger the car has been to the dealership maybe 4 or 5 times. I'm using stock plugs re-gapped to. 025. I have not touched the plugs since regapping them in April. The car will ru the same with the tune on or off.
There seems to be a lot of confusion that can be cleared up by searching the Stinger forum's tuning section.
Here's a thread on spark plugs and tuning for your reading pleasure.
How to avoid blown spark plugs in your tuned Stinger