SCT tuner with lifetime 5* tunes from stage3motorsports, couldn't have been happier with the product, service and support you get from both Mike at 5* and especially Bill at Stage3. Cant tell you enough just give a call over there and talk to them about the product and the tunes you will make the right decision. To answer your question I got a ton more power, better throttle response, improved shift points and shift feel, better on-demand power and just about 3 mpg improvement on economy. And that was just with 87 performance/tow tune. Experience and driveability only improves with a little higher octane. You wont spend better money IMO.