No need for a front strut brace on a focus, it will give you nothing.
And if your going to have your girlfriend and child in the car please do not decat it, it will be VERY loud and raspy. Blue Finn is pants so dont waste your money. If there was one modification that i would definately do, above all else it would be the lightened fly wheel, woke the car up a treat and improves your 0-60 time above anything else. Get your car on the RR as it is, i think you will be suprised how many of the 168 horses it actually has...................... allot less usually.
Main thing is the ST170 is a rubbish daily, in standard trim they return an average 25mpg, tuned this gets allot worse, mine was averaging 18-20mpg