200-300 might get you 2 hp if you're lucky.
25-30hp is actually a difficult range to hit. You won't hit it with basic bolt ons. You have to get into actually building the engine, which is where labor starts to get expensive if you can't do the work yourself.
At that point, you might as well learn how to put together a homemade turbo for the same price and get way more power out of it (~80-120hp).
