mate, ITG are experts in the filter engineering field and their sole area of expertise is on the filters and intake systems on cars and motorsport vehicles. They know what they are doing, and the ITG has been proven to work without any issues, on the Cupra, S3, GTi and vRS without the extra cold air feeds, and has given consitently high gains.
Also take into consideration That andy@ITG used REVO's demo cupra as the guinea pig for this intake, with extensive dyno testing and never used any extra cold air feed. REVO now use this on their car over all the other potential intakes money could buy(and lets be fair money isnt an issue for them)and recommend it to other REVO users.
i think you are looking into this way to much, however another cold air feed will never be a
problem. it can only do good, but is it required........ i think there is plenty of proof that it isnt.