it gives you slightly more power, maybe 250-1000 rpm depending on how much you add.
that is a given for all sport engines (os,gms,tt,th,jba,sk,magnum,evo,ect) some st engines do not like above 5% nitro
on some engines it improves the idle (lowers it, makes it more reliable), on others it doesnt make a noticible improvement

on bushing engines the nitro advantages are not as noticible. due to the fact they tend to be ported much differently.

thats about all nitro does for you besides break the bank.
a gallon of nitro costs about 60-80 bucks depending on the market
a gallon of oil cost 20-25 a gallon
a gallon of methanol costs 3 bucks a gallon.
useing those prices, asumbing we are mixing 10% nitro heres what each individual ingrediant would cost
60*.10=$6 for nitro
25*.18=$4.5 for oil
3*.72= $2.16 for methanol
so nitro is by far the most expensive thing in our fuel.

im mixing my own fuel, 0% nitro, 16% castor oil, for 7 a gallon. if i add 5% nitro its about 10 bucks. thats all i will ever need, no sense in paying 15-20 bucks for a gallon at the hobbyshop