I'm with everyone else...Tune and STS or STS and rear motor mount. I have a CFM Adjustable STS and I love the way it feels. I'm getting my rear motor mount this friday and I'll be getting my tune more towards the end of summer after I get some more of my performance parts installed so I can't really tell you the end results of those but just by reading a few posts on here I think you can get the idea of how good they are 
How about tuning the nut behind the wheel by attending a HPDE with instruction?
The SVT Focus is far more capable than the average owner can appreciate. I do not understand the rush to spend money to "improve" a car that works well out of the box.
it's not a waste of money it is probually the best bolt on you can do besides a tune and
fi if he does not want the car to be loud then he can get a random cat pipe that also would take the worry out of him getting fined if that would ever happen and for emission purpose