I wouldn't suggest using nitrous to spool a charger for street use for a number of reasons. Basically, probably not your best bet for constant use. There are a number of good nitrous systems out there, but I think you may want to consider other possibilities. I'd say go with a 12cm housing on your charger, that will help with spool, just give a little up on top.
Think about how a nitrous system would work, it would have to come on in every gear to help spool the charger at every shift. I don't think it would be too practical for your use. Would likely get costly along with being illegal on the street. Also, bringing nitrous on at low rpm's is a bit hard on parts - although you likely would be using a small amount. For performance applications, nitrous is extremely efficient and effective, but it is or should be applied precisely. Just my opinion, I'm sure others will disagree. I'd look in to a 12cm housing if the 14 is too laggy.