Tom's kit is what they'd call "complete", in the US. It has a bigger MAF sensor, as well as a chip to remap the engine..

The problem with this approach, is that MAF sensors don't measure actual boost, just airflow, for that you'd need a MAP sensor, and perhaps some actual tuning.

Also the US focus has a returnless fuel system, unlike our european ones, which according to more professional people than myself, means tuning is less of a problem for us, than it is for them. I'd personally reccommend you take advantage of the dollar by buying a "turbo kit" with the turbine, tubes, and intercooler, but sort out the tuning part here in europe, best would be to get a standalone engine management system, such as the pectel t2.. also I hear good things about autronic, and maybe even a piggy back unit such as the smt-6 could work out.

Personally, I'm following this approach for my car, and building an MSEFi computer for tuning.

Also, if you're doing this, don't forget to start thinking of ways to lower your engine compression ratio, and you'll need bigger injectors, colder plugs, and your gas pump might need to be replaced or helped, once you're seeing 200bhp+ (Not 100% sure about the gas pump, people of knowledge, please confirm/reject my claim )