This might sound stupid, but if you wanna tune the 145 then go for the 1.8, cos its a 'square' engine, i.e the bore and stroke are matched, over square - big bore small stroke, like the V6's is the best. the 1.8 is the best comprimise, the 2.0 is undersquare, thats why it needs the balancer shafts.
But if you want performance out the box, cant fault the 2.0, its a stonking engine!!!
Induction kit (CDA box)
Full supersprint exhaust
Cams (reprofilled-cheap, C & B-bit more expensive)
Eibach springs/Koni yellows
And a real remap on the rollers, not a guestimate job!
Or if your serious, throttle bodies and an aftermarket ecu, see Ahmotorsports.co.uk
Imagine the sound of that at full throttle!!!