I have one and noticed difference but only slight. If I were to rate its value for money, I would only pay half the price.
In any case, if you want more power, just donate your car to habitat for humanity and buy a gas guzzling monster like the RX7. They are cheap, fast&fiurious look, spades of power and most of all....f*ckin dangerous especially when powering our of a roundabout.
I have learnt my lesson. My next car will be the next Fiat Coupe turbo if there is one.