one place that i can recommend for parts for both 2 and 4wd z24 motors is 4x4parts.com, they have a decent inventory of parts for hardbody 720 and frontier parts. They offer a camshaft for the z24i that will work with the stock valve train and reports an average gain of 10-15%. Like everyone on here is telling you though with the head design of the z its not going to allow for massive gains w/o going forced induction... the L head is going to be a practically zero mod bolt for bolt swap, if you have difficulty coming up with the head u can improve the performance marginally especially in that small of a truck you will have a blast. gasket matching the head on both sides, the cam good plugs and ignition components will make nominal power gains, and a header may net u 1 or 2 hp but it will make the truck sound very nice when mated to a good exhaust system, you can also get computer upgrades from there as well. they may only get you 10hp or so but in a truck that only stocks @106 thats a pretty intense gain comparitively speaking.