ahh yeah they are k series, but the weak sauce k series, the k20a3 160 hp... back when they could bloat the hp ratings. and they do not have vtec as most would think, its the vtec e crap.

as far as an a2 head swap, you wind up with a head that makes most its power revving really high, and the a3 shortblock just wont do it, its factory redline is 6800, pretty low, increasing that another 2000 rpms = carnage. it will be a boost in power but not sensible. and you will also fall out of vtec every shift because of the dumb a3 transmission..

i am thinking also about the k20z3 swap from the 2006+ civic si. 200hp with 6 speed lsd.... the biggest attraction is the lsd. there are a few differences as far as the swap goes but im still researching that. but the mileage on one of these would be much less that an a2 swap.