If you get a civic ex, turbo or nitrous would probably be the best bang/buck in terms of performance, but a swap would be a little more thorough. If you get a DX, CX, or HX, I would recomend an engine swap over F/I. If you have a lot of money to throw around, a swap and F/I is the best way to go. How much money are you thinking of spending, and what are your goals for the car?
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