Without ripping my engine apart and spending thousands of dollars I would like to know if there are any improvements in Horsepower that can be made for a reasonable cost. . My research shows that exhaust headers, cams, port and polish are super expensive and you get very little game. The Squadra chip seems to be a simple solution. But needs 93 octane fuel. It also gets mixed reviews. My S4 only has 50,000 miles on it. It seems to be struggling in the higher RPMs. In years past I had a 69 and a 72. They revved freely to the red line and wanted more. . Thanks for any recommendations.