I am not too far away from you.
I keep the Swedish made Ferrita systems in stock.
Cat back in 2.5" material with resonator and rear box with two outlets £345.
Downpipe, one piece, in 3" down to 100cel premium Kemira/Ecocat cat then 2.5" to the mating flange £555, both prices including VAT.
I offer warranty on faulty materials and construction for as long as you keep the car.
I am in north west London and Prestwood nr. Great Missenden and you can have a run in my own ST with this kit on.....
Ferrita systems are not noisy but do change the exhaust note both inside the car and outside.
You can check here
http://kalmar-union.com/parts/ford-focus-exhausts/
Regards, Don.
You can call me on 020 8959 3230....I am available weekends as long as we make a time.