COOL!! So I did all my mods before the tune. I lost throttle response because of the reduction in back pressure. a slight in increase in hgwy mileage and mid range power. My base tune was turning the speed limiter and torque vectoring off. Increased the ignition timing +5 degrees. The computer will adjust too the new air/fuel mix. The speed limiter lives up to its name. cut off is 117mph and it starts kicking in around 90mph so its gradual. Thats where the benefits of your mods are in their sweet spot. w the tune, throttle response was back better than before and mid and top end power can be maximum. You can do more timing and degree cams too bring even more power sooner but i didnt go that far. Plus I run 93 octane for a cleaner engine and prevent detonation from the advanced timing. Plus it makes a little more power. I think it runs great now. Id guess around a 20+ hp gain in the end.