Long term the plan is to go for 300bhp. After stage 2 it gets really expensive though. Your talking bigger turbo for anything above stage 2.
As for Revo, they are concentrating on the VAG cars at the mo. Ford STs and RSs account for roughly 5% of their stuff so I've been told to expect a long wait for news of their stage 3 and upwards packages.
Went out, as a passenger, in the Sitech 375bhp Fiesta ST whilst my car was being tweaked. That thing is an animal. Fastest car, by a long way, that I've been in.