Mine has been fine, runs good, power is quite smooth but I get a large amount of power halfway to the end of the rev range due to my inlet setup. I put the inlet back to standard and it was just smooth all the way though.
Quite a lot of people are surprised by the car, I have had a Focus ST owner on the motorway shouting out my car is fast and a few others lol.
Economy wise I can't say, as I have quite a heavy right foot unless I am on the motorway for a whole tank, which I believe gave me 38mpg at 70mph.
Average is about 30mpg with all my modifications.