From what I can gather about the integral head, its not so bad- probably as good as the non-integral head, but you just cant really work on it. So to stay stock, no real reason to change that.
A good spark curve will help, maybe see if it likes a little richer jet. Get rid of the hot air tube to the air cleaner especially for the summer, and run a taller filter element that leaves a gap at the lid like an open air cleaner.
That's really about it, other than the EGR the smog stuff doesn't really hurt performance or mileage much. The air pump takes very little power below 5000, I clocked a rig once with and without, not even a tenth of difference in 0-60mph.
You can do that simple stuff and it will still look stock, and not sink a bunch of $$$ into it either!
