2) Same, but rebuild engine using custom low compression pistons for 93 mm bore (preferably forged ones). Then, you can do everything you could do with a 'straight' turbo engine.
Caveat: the 2.1 litre blocks seem to be cast from slightly different (and inferior) material than the 2.0 ones. Lots of documented cases for block erosion and subsequently, failed head gaskets. There's a bulletin somewhere (www.townsendimports.com probably, when its up) that tells dealers to fix blocks thus aflicted using some kind of epoxy.
For this reason, to turbocharge one of unknown condition might not be the best thing to do - so I would probably open it up and go the rebuild/custom pistons route sooner or later.
Presumably the capacity increase from 2.0 is a result of an over bore?? If so, and the rest is standard 16v injection, then you have the traditional non-turbo tuning mods to make - cams (Abbott? Heuschmidt?), exhaust manifold/system (Jetex, others?), injectors & fuel pressure, porting of head, blueprinting, lightening & balancing of reciprocating components, possibly throwing away the stock FI & engine management and replacing with bespoke injection and ignition (Weber Alpha, throttle bodies etc). You could even throw away the FI and put some nice fat carbs on, and have hours of endless fun balancing them and stopping them spitting fuel out at you
That all sounds like a lot of effort (and cost !)for minimal gain to me. What are you going to get, 10-15% increase?
Better off starting with a turbo methinks! It's not as if they are in short supply!!
AH, typed my reply but didn't post for a while as the phone rang and have now read Eric's reply. This whole 2.1 block is a new one to me, so scrub my coment about an over bore.
Eric, would you mind enlightening me on the origin and use of these 2.1 engines?
Not directly answering your tuning question, but have you tried a non-turbo C90016v ?
I bought one some years back, having never had anything but turbos, and I expected it to be sensible, but slow and sluggish.
I was (and still am) impressed. It doesn't have turbo torque-rush and it clearly doesn't have a lot of power (60-80mph up a big hill will take time), but it remains fun to drive. My car is a 9-5 Aero and when I borrow 'her' 900, sure it feels slower, but still leaves most other traffic comfortably behind.
I also find, that in Saab-ish style, it still has good low-down torque in spite of being 16v. Try driving an old Honda or a VW 16v and you need to rev. like hell to make them go, not so with the Saab