Welcome to Pf and congratulations for actually driving a Ford as half us don't seem to these days

Agree with above, a K&N cone filter improves these no end as the airbox seems really restrictive. Rather than spunking your £300 each month on bits build a plan and save up to do the work.

A friend of mine had the Mountune 185 kit on his ST and it went quite nicely and sounded good too.