I've been running lowest octane with stock exhaust for emmission testing, plus I am at 5300 ft or more elevation where I drive. Just wondering with a ported wastgate and going back to RB Turbo back exhaust if I could get a way with mid grade or low greade gas. Without ported wastegate I had been always running premium 91 octane.

I replaced the turbo because the seals were bad and looking at the turbine housing is was very white, looked like it was running a little lean. But that was running close to 10-11 psi. Now that I have the wastegate ported should just see stock boost across the rpm range. So you know every penny counts too. Just wondering if I could use lower than 91 since I have the WG ported now.