I had a hondata tuned Civic turbo as my last car. pushed 229hp to the wheels, it was pretty sick fast in the light EK.
the k20 can be easily tuned. There is a head kit for it dynoed at 270hp.
Remember though, just bolting on a turbo doen't make you fast. You'll need the proper fuel managment and tuning. I spent close to 20k on my civic and it was the biggest waste of my money. It was fun when running but high hp cars tend to break down often, (plug wires going bad, piston seals losing compression, gaskets going bad, oil all over the engine bay, constant fuel smell, I can go on and on. Had the turbo for 3years and got tired of wasting all my money. Bought a MSP and keeping it stock. Tuning cars is a money pit and make sure your ready to spend all the penny you have to keep it running.