i had nos on my last car. a calibra v6 with upgraded internals.
it last aas long as you want it to. it depends on whether you want it dumping in in ts entirity or in stages.
a full 11lb bottle can last 10 sessions using maybe 5 times inthe one session.
refills average about £5 per lb but that doesnt botther you.
if you are going to do it i suggest a progressive controller is a must. this means you can effectivley control the amount of nos you are using.
60hp is not worth the hassle really you wont feel that much.
i had a 75 shot running and you felt that but i would get a 100 shot and use it progressively that way you are equallying the tt spec albeit for a limited time but it certainly kicks you in the ar*e.
anything else fell free to ask.