I am considering installing after market intake and exhaust systems on my 2000 Toyota Celica GT. However I would assume that a modern sports touring car such as mine would already be fitted with a good setup out of the factory. The 1.8L 4-cylinder engine needs all the help in can get. In other cars I could imagine there would be considerable benefits to after market parts in this are, but I am concerned that I would not see considerable performance increases. If this is the case, where could I see the best value for my money without installing a turbo, supercharger or NOS?
Please do not listen to anyone who tells you you will get 30+hp out of an intake and exhaust system on a bone stock N/A vehicle. That is a flat out lie. If you're looking for true HP the cheapest way would be to install an aftermarket camshaft with a more aggressive grind than you have currently. This WILL add HP because your valves are being lifted more and for a longer duration, thus letting more air/fuel into the engine. It will run you about the same price as an intake/exhaust system, just under $1000 but you will actually see and feel a difference in the way the car performs. It will rev harder and faster. On my 1995 Celica from a camshaft change I saw a consistent 10-15hp gain going up the RPM band starting at 2800, with a peak gain of 25hp, and a redline gain of 20hp (usually where the engine starts to run rich and is just getting flooded with fuel and the power drops off) As for the cold air intake put it this way your car most likely already has one that runs straight to the front of your bumper. so how would changing that so it now sits behind the bumper change your hp? As far as an exhaust, unless you're running a full header-back exhaust with a high-flow cat, you wont see much of a gain because there will be a choke point somewhere in the system, and if you're staying N/A you shouldn't run anything larger than about 2.25/2.5 inches. If your going turbo you run a 2.75-3 inch and larger (depending on the power you're putting out). Hope this helps. (most of the hp claims for aftermarket parts are at the crank, and not the wheels fyi, and a 30hp gain at the crank especially with something as simple as an intake/exhaust, translates into at BEST 10 wheel hp. The figures I gave you for my celica's HP gains were AT the wheels.)
A cold air intake will be the cheapest accessory, with gains of about 10-15HP. After that, swapping out your header and cat back exhaust will add together maybe 20-25HP. But, that set up would cost a little bit more. I have an '05 Mazda 3. With those upgrades, I went from stock (150HP) to just under 200.
