Are there any differences between these parts between the ST170 and standard focus models:

Steering rack
Roll bars

Need to know for a conversion

thanks

 

Steering rack is the same but it's shorter or has a limiter to stop the larger tyres (45 profile rather than 40 profile as fitted to special editions with 17" wheels) from rubbing.

Anti roll bars are the same.

 

would you not bother changing it then?

 

Nope, I'd just fit 40 profile tyres. You may even get away with some manufacturers 45 profiles without rubbing, Ford were just covering themselves. It will have a better turning circle, the ST170 is pretty bad for that.