To be honest its a bit concerning that you don't know if its a turbo-diesel or not, a fully fitted (K&N) kit would have a section of pipe to fit the MAF, and places to fit pipes/ breathers etc, without this its difficult to fit the cone

on top of that the K&N under the bonnet is liable to draw hot/ warm air (worse on a diesel) which looses power, because of this open cone filters have become less popular now, heat sheilds/ cool air feeds are often used, or better still fully encapsulated filters (BMC / venom etc,)

if you managed to fit the K&N cone filter it may just make more noise and loose power

or even a panel filter, as LD has suggested, probably less hassle/ cheaper in the long run