Looking through the forum I found SOME answers:
Type S engine number is F22a, 135 hp @5299 rpm

But the bloke says that is 2159 cc not 2156 cc like the F22a should be?
Looking at the spec for the SI and the VTEC none are 2159 cc?

Do the SI and S have the VTEC rocker covers?

Here's a pic of the engine bay in question:
http://www.ballandboyd.co.uk/glyn/5f_3.jpg