How to maximize horsepower in my 2013 ford focus SE?

Listen, I have a 2013 ford focus SE with 160 hp stock. I'm trying to boost my hp up to improve performance. I have already got a injen cold air intake. I need other ways that arent to hard to do, or exspensive. I don't want to make my car look dumb, so don't say "add a cool loud exhaust and a spoiler." i'm not trying to make a not fast car, totally fast. Just boost the performance. So please, i'm looking for simple things i can do. The injen air intake was 270$ and is said to add 10 HP and boost fuel economy. PICKING BEST ANSWER FOR 10 POINTS.

Not going to happen. I don't care who you are, you aren't going to improve performance without improving airflow THROUGH the engine. Waste money on intake and exhaust (I see you already have) and it will do nothing.

You really, really need to learn about motors. You can't increase power and economy. They are mutually exclusive, period. I'm not here to tell you that you are stupid. I'm telling you the REAL resources are out there to help you learn about engines and how they operate. It isn't some theory, it's empirical evidence. You notice that companies such as Injen aren't going to post actual dyno tests on your car and your engine. Every vehicle and drivetrain combo is different, if you buy into marketing hype, you are going to have a miserable life.

YOu shoudl write this down and keep it handy Use ONLY AMsoIL or MOBIL ONE 0W-20 engine oil that will maximize power and lower friction. Remove the STOCK plugs which are VERY GOOD, but replace with either BOSCH IRIDIuM or DENSO twin tip plugs. AMsoil is good for 25,000 miles or ONE FULL YEAR between changes. It will keep your CONVERTER and O2 sensors cleaner longer and more.