There are many performance parts that you can add to your car to add power. There really is no limit as to how much power you can add, it depends how much you want to spend.
Everyone else has honestly forgotten half the expenses.
This is something you want to put some nice research into, as far as what your car can handle, and a cost analysis. Study the forums, or contact a local performance shop that has a decent reputation and talk to them.
Some of the most power packing performance parts and turbo kits, super-charger kits and nitrous kits.
Then there replacements for just about everything under your hood. Some of the basics you want to start with are the air intake filter and the exhaust if it is the exhaust that came with the car.
Once you research the car you have or are going to buy, then you should have a good idea in how much you are looking to spend. realistically, you want to plan on even more for any unanticipated parts, or any that were missed in you research, as you really find out what you need when you or the shop actually puts it all together.
The most effective and also most expensive performance parts that you can ass are a turbo kit or supercharger kit. These need a bunch of components to run right, in order to re-tune your engine to match up with the extra airflow you are throwing at it.
Turbo kits are perhaps the most significant modification you can make to your car to increase the maximum power and performance. Super-chargers are quite equal, yet they just lack the top end potential due to having a bit of rotational power loss from the supercharger belt at high speeds.
There are many factors to take into consideration if going with a turbo is your goal. First you will do best if you have a set of realistic goals. By realistic you will want to consider what your budget limits are, and the limits of all the mechanical engine components are.
To attain any significant increase in power, your motor will need some sort of reinforcement, whether the cylinders are sleeved or made out of cast iron, the pistons and rods made sturdy enough, whether the rods are cast or forged and the pistons cast or forged.
Once you know the capabilities of horsepower your engine is built for, then you take into consideration the displacement, and other factors such as safe rev limit, in order to decide on the dimensions of your turbo.
Bigger is not always better!
Many people think if they just get the biggest turbo, then it should follow that I get the best performance, right? Not at all. When your vehicle breaks down, you must get it to run again. Not having a reliable vehicle will make your entire life complicated. But, you may not need to spend lots of money to solve the problem.