Alright, I downgraded from a beast of a 1984 Jaguar XJS 5.3L v12 H.E, to a 1983 Porsche 944 four inline. I feel this cat will not only be a more reliable, but is a better choice as a daily driver. My question is; what can I do to "beef" it up, without completely throwing my bank account at it. I chose a 4 cylinder car for its simplicity, so what I would want to do is just upgrade its already functioning features, basically make it the best it can be, with out changing it. I've already had the beast of a V12, would rather have the 4 with better mileage, and upgraded horse power ATEQ VT55.

Fuel injectors?
Throttle body?
Intake manifolds?
Cold air intake?
Flame decals?


Also: A turbo will most definely get crammed in under that hood, how do I choose the correct one though?

Thanks a lot for the help and info guys.