I doesn't really matter if cosworth had input or not you can't call a Ford Focus st170 cosworth tuned unless it's been either fully developed engine wise by cosworth or they have drastically changed it from a standard ford based engine and they've gone to town on it and then iam sure cosworth would of ask for some markings or stamps on casting or components to let people know they had a hand in tuning the car. A bit like mountune or wolf or even the cosworth badge itself and even that rs badge which are all approved ford tuning companies or branches owned by ford.
I wanted to throttle body mine after going in my mates 250 bhp type r as he chucked about 4 k on secondhand parts to get 30 odd bhp from his engine . The bolt on kit from jenvey etc isn't that good I've heard it only takes the car to around 190 / 200 bhp . I was going to go tapered independent throttle bodies , big valve head , and forged Pistons but couldn't be arsed as it was around 4 k and then you had management on top of that so decide not to do it. I would love a 280 /300 bhp on bodies thou they sound quality
Cheers Paul