Don't expect such a big difference with it on the B series mate, doesn't have the tuneability the K20 does via the ECU route although gains will be made, they aren't as great as the K series
Also it's not as straight forward, OBD1 ECU needs to be sourced, then the S300 fitted, plus a OBD2>OBD1 conversion harness. Or you can pay more to buy a complete ECU direct from Hondata, which is ported with OBD2 to OBD1 sockets so plugs straight into t he existing loom, which works out a bit more than Kpro