I have just recently purchased a modified 2007 gt500 that is tuned for 93. Makes around 650 rwhp on 16.5 lbs of boost through the stock exhaust manifolds and cat-less H-pipe (Other mods in sig). Unfortunately from my location the closest top tier station with 93 is 40 miles away. Fortunately there is a Harley dealership within 2 miles that has 91, 95, and 100 on pump that is managed by their service department. The 95 is a mix of the 100 (Sunoco 260 GT) with the straight 91. I am planning on running this until I come up with a better solution. I was able to contact the company that previously tuned the car and they thought it would be fine running the 95 as long as the mix is consistent but still suggested I get on a dyno to verify the A/F ratio and to check the timing marks on the spark plugs. So my question is has anyone else run into issues running a race gas mix when the car was not tuned on it? Or does anyone see any potential issues? I will have it on a dyno in two weeks to verify the A/F ratio. I do not think I am going to bother pulling and checking plugs. The plugs in it probably have less than 1000 miles on them. I realize that a new tune would better utilize the higher octane and gain more power but making more power is not a priority.