ZREXER --
I recently had the MP215 kit installed by my Ford dealer. I created a similar threar on another Fiesta ST forum and here is my cut and paste of my update after the installation:
"MP215 Kit was installed today by my local dealer. So far so good and the additional power/torque is definitely noticeable across the rev range but especially it seems in the mid-range starting around 4000 rpm. I can also detect a bit more aggressive intake/induction noise and the exhaust seems to have a bit more of an aggressive bark. Overall, a nice upgrade at a great price that does not overwhelm or radically change the overall balanced nature of the car. Thanks Mountune and Landmark Ford!"
I have been extremely pleased with the MP215 kit and the installation by my Ford Dealer (for which I was charged $175). This is the only upgrade I would have contemplated for the ST because of the fact that it woud not void the Ford factory warranty.