Modifying cars is not a cheap hobby. Lucky for you that you have one of the cheapest cars to modify. Honda makes some great cars and thus they sell a lot. That is also why Honda has very large aftermarket support. There are many companies that make products for the Accord. Unfortunately if you are looking for serious power gains it is hard to come by unless you are ready to spend some big money.Bolt-Ons are your best bet here. Intake, exhaust, and headder. AEM makes some of the best intakes for the money. They are a little pricy compared to E-Bay intakes and all but always remember when working on a car, you get what you pay for. AEMs intakes are engineered for the car. Make sure to get a CAI (Cold Air Intake) as opposed to a "Short Ram". Short ram intakes will give you slightly better throttle response but not real power. That is cased because of many reasons including the fact that they are sucking up hotter air from the engine bay. But the issue with CAIs is that they can injest water in bad flood situations which can hydrolock your engine making it useles. Exhaust has multiple parts to it. You can change your Exhaust Muffler for a better flowing one and also you can change your pipes to 2.25 inch pipes. This will help a little.Headder is another thing to get. I would sudgest a 4-2-1 headder as opposed to the 4-1 headder. That will give you the power in mid range as opposed to high range. With these boltons you may gain about 10 HP or so. Not too much. Another thing is tires. Make sure you have the correct size for what you are doing. If you want more power then you would be looking into cams and valve jobs and eventually into forced induction which is not cheap.