Hello newbie, FB here, i've had my 748sps bigbored to 853cc as have several other board members. Although this in no way relates to your 955 option apart from in technique, you'll find that the extra bore liberates up to 10-15 extra horses depending on what other work you have done, ie blueprinting, porting, skimming and gasflowing etc. The rise in torque is the most favorable aspect apart from the power gain it starts lower in the rev range and has a flatter curve which extends way up the rev range. As an example my sps now makes 110bhp and 65ft of torque at around 9000rpm. When it was a 748 it topped out at 102 and 55ft. I've not had the engine blueprinted or gasflowed. One of our board members KJ has had the full blown jobbie done by JHP with all the aformentioned extras, and his is putting out 118bhp !
I'm not to certain of power figures for a 916sp but i'm sure it's around 106. With the big bore you'd be looking at a real rev monster. The only problem I can forsee is where you go to get the work done. We all swear by Sigma, AJ racing and JHP, but there are others. If it were me, i'd give them all a call get some quotes and info and go from there. Sigma's web site has bucket loads of info on all this stuff to, as does the old message board; just do a search, i'm sure alot of old posts relate to 955's and such. Good luck.
Pssst... senoir, Alan at AJ racing in south glos is the cheapest
[Edited on 31-5-2003 by flyingbanana]