the Z6 will work just fine. i would do the head swap/intake manifold swap and run it on stock gaskets for now... if the car runs a little warmer than you'd like, go with the hondata. i personally have never seen any power gains, nor do i think they would be even recordable. maybe 1-2 HP, but doubtful to me. and you don't want a car that won't warm up to a certain degree. check the specs on tempurature for optimal performance. then if you wanna get really crazy, add an aftermarket temp gauge and see where it runs...then go from there. on my old EF it ran too cold all the time with the hondata...so i had NO VTEC unless i was in phoenix (which is hotter and less altitude) so i switched back to the stock one, and VTEC worked properly everywhere.