It depends but at a mile high, like Denver you can use the 85. I don't think you'll have a problem. Anything under 5K feet I think they're selling nothing less than 87. The safe way is if they have 85 at your level then it's safe to say you can use it. If you're at an elevation that sells both just try the 85 and keep a bottle of octane booster on hand "just in case" it ever does start to knock. I doubt it will. The SVT guys are the ones that will need to play with this more as well as the guys with chips.
John
