I doubt the piece you have a link to will make a lot of difference. It certainly won't reduce the air temperature further from the stock system which is pretty good and I would retain the O/E airbox unless going for big power.

 

Just as an update I have since fitted an Apexi kit due to installing a FMIC so the resonator has been replaced.

When I had my car mapped back in June by Andy F one of the things he said straight away was that it is a good idea to get rid of the resonator for better induction air flow.

Obviously it would need mapping to take advantage of any improvement.