The saloons arent as often modded as the hatchbacks but when they are they look pretty sweet.
If you want to uprate the sound system Id bin the standard headunit as its fairly restrictive.
Any wheels for the focus will fit the saloon so get yourself looking - multi spokes look pretty sweet on the saloon. It is worth dropping it maybe 30-35mm to get it to sit right on bigger wheels.
Any focus front bumper will fit and theres literally hundreds of different ones out there - some nicer than others

. Have a look at the ford collection front ends as they are pretty tidy.
If you have a look on
www.ffoc.co.uk theres a couple of saloons on there. Ive stuck a few pics below:
Andys Saloon
One of the turkish members
Rich