What is the best way of improving the power of my inline 4?

So my vehicle is a 2011 ford escape xlt with awd and an l4. I would like more power from it. Getting the v6 was not an option. And I will not be getting a different vehicle. I will be using this vehicle for a long while and would like to just give the 4 cylinder a little extra. What is the best way I can go about this? Stock it should have about 171hp. I'd like to try and get it past 200. I do have some money but I can't be putting anything like 4 or 5000 in it. I don't know as much about cars as I would like so anything you can tell me is helpful. Unless you are telling me not to bother then don't waste your breathe. If you know of any parts and you can link it to me for my model it would be much appreciated. Thanks

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