Octane has nothing to do with carbon build up. Just use a top tier fuel.
https://www.bellperformance.com/blog/bid/112387/using-premium-fuel-in-your-vehicle#:~:text=Cleaner%20Engine%3F,to%20do%20with%20the%20other.
No such thing as " pre detonation " most modern cars are 10:1 or more. Vvt helps them run 87 octane.
http://www.new-cars.com/2012/ford/specs/focus.html
Madstad bar is 22mm. Found simple mount on Ebay.
https://www.ebay.com/itm/255614587174?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=kSmY2AJCT8K&sssrc=2349624&ssuid=wqxmobmRQri&var=&widget_ver=artemis&media=COPY
Apparently the original owner was too fat to ride it. Owner I bought it from got it with 500 miles a year ago. Alt rider crash bars and skid plate.I had a flash done by 2 wheel dyno works and have a Graves cct to install.