I would have thought fattening up the torque curve, the SAAB approach of a low-pressure turbo would be a better way to go.
That or simply buy a V8.
Doesn't every turbo require a lot of extra pipes and what not? Since my daily is a Saab 93 Aero I can confirm turbo's in Saabs are awesome!
But of you're going down the route of modifying... Fuel-injection might be nice as well?