I agree with rsdom! You have to decide on your own or ask your dealer for any modification you think about.
For myself I asked my dealer about warranty for following changes and he agreed on all that for warranty :
– Milltek exhaust
– Milltek downpipe
– Airfilter changes to K&N or other airboxes
– lowering springs to stock dampers
I know the dealer very good and it is a friend of my friends so if I ever would have anything bad with the car I will bring it to him.
And if there is a problem, I would just change the parts back to stock before any big spy’s from Ford will check the car. I also have the Dreamscience Ultima map on the car since over 3000km and will just load it back before turn in to dealer. I think and that is my own opinion and hope, that when my engine breaks (June 2016 car) they will just change engine and dont search a lot because they already had to much engine failures.
but this is also my opinion so feel free to agree or not 😀
Ford Focus RS / frozen white / fifteen52 tarmac / lowering springs kw / milltek exhaust / exhaust valve deleter / K&N airfilter / Maxton rear upper spoiler / Mishimoto oil cooler / Auto specialist 40% short shifter /