i've got a 2l w reg focus. had milltech cat back on for a while and then bought a focus central 4-2-1 manifold used off a mate that needed a crack welding up. actully it looked like one of the collectors had never been fully welded up

as its a LOT longer than the standard manifold it romeves the cat aswell and i noticed an instant improvement...especially past 4k. i'd kinda got used to the way the car pulled when i booted it before the manifold but after it shot me back into my seat again!!!

personally i wouldnt bother with just a decat as the standard manifold is too short and crap! better off going st170 manifold and cat and flexi as that'll make the best gains and decatting the st doesnt make uch difference if any...although sounds awsome