[milkcrateracing]

Originally Posted by Jim Schornack

I have owned my GTP for about a year now and the previous owner claimed he never ran premium fuel. He also said he has had no issues because of it.
I have read that the supercharger will not operate properly without premium. (loss in performance) Will running regular fuel hurt the supercharger or engine?

FWIW my GTP pinged big time on regular when I got into it. I only ran one tank and switched back to premium. Most of my driving was between 4k and 8k elevation which should lower the CR and performed better on regular. I think GM recommends premium for a reason.