I mailed the guy's at :worship: DTR :worship: a couple of months ago for their opinion on the whole 'induction kit subject'. They were very helpful but said they do not recommend fitting an induction kit as you gain very little in the way of BHP and often upset the airflow meter in the process. Their advice was to go down the route of the K & N filter as it increases the airflow without the need for a change in setup, also is much cheaper in the longrun as you simply clean it and stick it back in at each service.
Various RR confirmed that the Punto HGT induction kit (Barchetta 1999->; thanks docorangepeel ) improved peak power by over 10bhp.
What I don't understand is why an induction kit should upset the airflow meter??? Having designed quite a number of induction kits I have never come across the induction kit being responsible nor have any of the competitors. K&N have for less than 1 in 100,000 sold a claims and so far not as single of these claims could be verified.