I have a 2001 honda civic lx 1.7l. What can i add to it or do to it to make it go fast?

Id want to increase hp. But i'm on a budget only can spend 400$ thank you

You want power, it's going to take more then $400. If that is all your going to spend, then you better off just saving that money.

Not for only $400. You'd be wasting your money.

Forget it, that car was not meant to go fast.

CAI and exhaust and tune

All of these answers (except Anonymous) are correct. You have the "Black Sheep" generation of the Civic. The D17 is not the engine to do anything to. That was the only generation to use that engine. The only option for it )for effective performance) is turbocharging, and even that is a waste on that engine. You'll want to rebuild the entire engine with forged internals, modify or swap ECU and upgrade the injectors. Trouble is that for that kind of money, you can do a K-Series swap and have equal performance and with the better durability of an NA engine without the complexities of forced induction. Then you'll have room to really grow if you wanted to boost it later. Performance doesn't come cheap.

Have the valves adjusted first. All Honda motors have a common problem with tight valves and power loss. They need adjusting every 60,000 miles.
Then buy a Borla cat-back exhaust system.
Don't get suckered into buying an after market CAI. Your vehicle has one from the factory. It just happens to be plastic with a convenient replaceable filter.