K is better in every aspect, the trannys are weaker than bseries, The 6speeds work great for motor setups and the 5speeds work good for turbo setups. a basic stock k20a2 intake, good header kpro will net 210-220whp.

for example,
here is stock k20a2, IPS k2 cams, supertech valvetrain, RBC intake manifold, DTR header, kpro tuned by me ( the only graph i had left to overlay at a big dip in it lol which did get removed )
Vs.
84mm ls vtec 13:1 toda spec Cs, square port head CTR head, square port ctr manifold, hytech header, rpm service 70mm tb, hondata