Again, I said this in the other thread you made, but I would not P&G this car because the Valvematic makes it far more efficient at low load than a typical engine, and you only have 1.8L to pull a fairly big car (compared to my tiny sports car). Because of this, its peak efficiency load should be a little lower than most engines (my guess is 70% rather than the typical 80%), and so more modest acceleration will help your fuel economy.
The only mods that I would try are load reduction mods, like an underdriven water pump, reduced electrical power usage, aero, etc. You can buy an underdrive pulley for the water pump for 75 dollars off MWR (I think the 2ZZ-GE pulley is the same as the 2ZR-FE pulley, and they are interchangeable), but you will never save anywhere close to 75 dollars in fuel from that mod.
While you can't have fun modding your car like most other people here, you can enjoy the fact that you have one of the most advanced engines out there that does all the hard work for you
