Ahah! Got this back from mercedesperformance.co.uk
Dear Steve,
The 4 cylinder engine ranging from the 180 to the 230K is the same size and differs simply from a software perspective.
We are currently working on a new program for the 1.8 ltr engine.
We have other performance upgrades available including the complete puley kit and intercooler upgrade which provides approx 65 bhp extra and superb improvements in the low and midrange sectors. Acceleration also improves substantially. The kit is priced £2900 + Vat fitted.
We also have twin and quad tailpipe performance exhausts and induction kits available which provide increases of 5 - 12 bhp. Please see the attached images of some models we have upgraded.