I have owned dozens of cars over the years, both economical and high performance. The manual says to use regular and that is fine, but I have always put a tank of high test through my engines from time to time and can notice a difference in idling and performance. Try filling up with a high octane and detergent gasoline after every four or five tanks.I would also suggest you use Synthetic oil in your engine. Set the date and mileage for 5,000 miles or five months. It is a little more expensive but better for your engine. Plus, you get another 2,000 miles. It does not break down like regular oil.