i would go with a b18c1. and if your going to build it, build it for turbo. as for the b20- the b20 does not have vtec, and i think it has a very low compression ratio, like 8.5:1 but i could be wrong about that. if a b18c1 is a little to much, do to the b18b, it doesnt have vtec, but it will be a torque monster when turbod. there are other people on this forum with ALOT of knowledge on turbod b-series motors. like WestCoastStyle. he has a killer setup. if money does end up getting tight, why not just build your d16z6. it may not be DOHC, but it can deffinitly hold its own. if you want to know more about that, try turbod16.com and sohchonda.com. there are people at these sites running in the 13's and 1 guy in the 12's with a stock bottom end. of course they tuned VERY carefully, but its possible. and as for the b16, i wouldnt recommend it. yes, it is a cool motor, but what you spend on the SiR II you could easily make a respectable setup with your d16. that is just my .02. due with it what you please