423hp / 396tq After Proxses Street Tune! Here's my cam-only 2005 GTO on the dyno after Proxses tuned it on the street. I couldn't be more pleased. I picked up 10hp/tq under the curve from the previous tune (done by another tuner). It made 423/396 at the wheels on a dynojet (click links below). I also got 26mpg on a trip from Dayton, OH to Florida with the cruise set at 79mph! Proxses' tuning services FTW!