What are some performance mods I can add to my 09' Honda Civic Si without hurting the lifespan of it too much?

I will be commuting 50mi. Each way once college starts this summer so I won't be able to add any sort of turbo/supercharger. I'm planning on getting an intake, throttle body, and headers. Just wondering if I can do anything else besides those listed ^ :)

What is your budget?

Intake is money thrown away, the stock cold air intake is fine. Unless you are running wide open throttle/redline a fancy plastic tube with a cone filter is worthless.

Throttle body can nab you a few hp for $400.

Headers about the same.

Basically, can gain a couple hp for about a grand…