I don't ever remember seeing any sets for the zxt. What I do plan on getting though is the 1 row euro pulley from MSA. Since I don't have power steering or A/C a 1 row pulley should help some. Not sure if you can go this route though...
But you could get an electric fan to get rid of some rotational mass from the clutch fan.
The Nissan dealer I get original parts from suggested I go to under drive pulleys to boost useable hp, so I know they are available for the zxt. I'll call next week and see if I can get a part number and vendor name.