I got a Active stage 2 kit with meth and I had it put on around 43,000 miles. Right now i am over 70,000 miles of daily driving with the kit and its amazing. It pulls hards and you won't be disappointed with the performance. The car drives like a normal car but when you mash the pedal its a another beast. Hot or cold the car will be spinning tires and you'll have better gas mileage. With the same driving style of pushing it sometimes and driving normal, I averaged stock(FBO) around 15.8 mpgs. After the blower i was able to get 18.4mpgs with the same driving style.
All Kits are amazing its your choice but i like having a company thats been around for a a few decades. If you got any question just send me a message.
F10 M5: 11.308 131.96 with a 1.9 60ft Street Tires
E90 M3: 11.2 126.7 with a 1.8 60ft Street Tires