[MichaelDay]

I concur that using higher grades of gasoline than recommended by the manufacturer is typically an exercise in futility. I also agree that the computer will attempt to back the performance down to match the lower grade of gasoline.

If you are actual hear pinging you can be pretty sure that the computer isn't being able to compensate for the grade of gasoline you are running. Remember that Chrysler does recommend Premium fuel for the HO Turbo. I am fairly certain that the PCM program in the turbo-lite and the HO turbo are significantly more different than just limiting the boost to 8 psi.

There are some who are not able to get 91 octane gasoline and the manual indicates that this is OK but you will experience less performance. Per the manual: "High quality unleaded gasoline having a minimum octane rating of 87 may safely be used for your vehicle. Use of these lower octane gasolines, however, may result in reduced acceleration performance."

As always you should avoid heavy spark knock. The manual (page 181 in the '03 GT manual) states: "Continued heavy spark knock at high speeds can cause damage and immediate service is required. Engine damage resulting from operating with heavy spark knock may not be covered by the new vehicle warranty."

In a nutshell, the answer to the original question is if they put a tank of regular in, problems should NOT arise in the future. If you are following the Chrysler recommended break in directions you will probably not notice the difference during the first 200 miles.