i think vocky was just teasing him, i wouldnt say you gain anything really, i didnt notice must of a difference when driving, but common sence tells you that its better for it not to be there..
i guess it did free up the revs a tad..
i had a race with my mate from 30 in 5th and 4th to 60 - 70 and it was dead even ..
mine had cold air feed to induction kit and pre-cat out, his was totally standard.