Id say go for it...if the engine runs fine a little more oomf isnt a bad thing
depending on the level of the increase you'll want to upgrade the rest of the valvetrain as well...or perhaps just update everything with new honda parts if the cam is rather mild.
Zex cams are very nice and very affordable...though Im not 100% sure if the d16a6's head will accomodate for the cams designed for a z6...of course you could always call and find out throught zex directly.
or...
http://www.hadamotorsport.com/D16camshafts.htm
they have a comparison chart for all three vtec heads and several cams