More Power - what's the best way to do it?

[Ex-Biker]

Got your kit car, had it for a few months now. You are happy with the way it drives and handles.

Now you've had it a while you are getting used to all the excess power you thought it had when you first built it.

Barring selling it and getting something else, what's the solution?

Just fit a bigger engine?
That's ok, unless you spent a lot getting the original 'sorted' in the first place.

Mild/major tune up?

Turbo?

Supercharger?

What would you do and why?

[LexSport]

Well I'm going to go for turbocharging.

The main reasons being, to increase the mid range torque as well as top end power.

Plus it'll be a laugh to see if I can get it working without blowing up the engine.