Please use the forum search this has been covered at least 100 times.
It will be faster with neglible mpg impact but could put extra load on the quite poor 2006 mitsubishi turbo - and in short you might end up needing a new one (But most people don't of course).
40 horsepower extra as a minimum certainly makes the car more fun though.
Previously: 2003 Peugeot 206 1.6 8v | 2006 E90 320d M-Sport, 19" BBS CH, Full Ice-cold JL audio install, August 2010 Total BMW 6 page feature car. | 2003 Nissan 350Z GT Coupe 286BHP
Now:2010 E92 LCI 335d M-Sport