for 200bhp you will need a intercooler upgrade which is the same as the focus 2.5 st's so uprated one of those will do.
A cone filter, cat back exhaust+decat will help to and a chip.
for the chip see stu @ msd or get a dream science obd unit

there is a chap out in belgium who runs a st tdci mondeo with a hybrid stage 1 turbo,uprated intercooler,cone filter,ss exhaust+decat and dream science obd unit running 230 bhp and 370lbft.
The chap is called david daniels he owns a belgian tuning company street performance
he sells the turbo's for £300 you need to add shipping to the uk also
david@streetperformance.be


here is some info on the exhaust
The Ford Mondeo ST TDCi exhaust system is available from:
JP Exhausts,
Goodall Street,
Macclesfield,
Cheshire
SK11 7BD.

Please phone 01625 619916
email sales@jpexhausts.co.uk
or log on to www.jpexhausts.co.uk for more information.