There are two cold air intake systems for the 2003-2004 Ford Focus equipped with the 2.3L/2.0L Duratec engine. One kit is designed for vehicles with automatic transmission and one for manual transmission.
It will fit a stock or Cosworth TB.
Perhaps you were thinking of how the Cosworth TB only fits the Cosworth Intake manifold without modification of parts.
Well if you did some research on Focus sport It says that it will fit the 2.0 duratec.In the stage 1 package from Cosworth it does not include the TB some a good guess would be that you do not have to up grade it.You do not upgrade the TB till stg 2.As far as the price for the CAI they run 349.00 is the standard any where you shop for it.