I received an email this week from a viewer who wanted to get 300 horsepower from the family's 135-hp, 2004 Toyota Matrix. I don't get requests that are quite that ambitious every day, but it brings up the concept of "bolt-on" performance upgrades that any reasonably handy owner can attempt. Whether these gains are worth the cost and trouble, however, comes down to how badly you want a 300-hp Matrix, Civic or Rio.
Here are the big four, with ballpark costs and power gains.
Turbocharger or supercharger: $3,000
This is the big one, in both power gain and price. Forced induction systems can add as much as 100 hp to our example 2004 Matrix -- and cost you around $3,000 for the privilege. That's half or more of the car's value, but much cheaper than buying a new, more powerful car. This is also the most complex of our "simple" add-ons and may tax the skills of anyone who hasn't taken an engine at least halfway apart (and successfully back together) before. Make sure whatever kit you buy keeps you in emissions compliance, and know that such a kit may void part of your factory warranty. But if you really want to put performance points on the board, this is how you do it.
Now we're up to 235 horsepower.
Performance air intake: $300
Replacing the plumbing and filter that let air into an engine with a less restrictive design can raise power by letting the engine breathe better at high RPMs. Some kits also claim to bring in slightly cooler air, which is more dense with energy-producing oxygen molecules.
That said, there's plenty of argument over how much difference an air intake can make, especially if you install a turbo or supercharger kit. But let's be conservative and say this add-on can give us another 5 horsepower. Now we're up to 240.
Cat-back exhaust: $500
Like a new air intake, a performance exhaust system basically gets out of the way of evacuating exhaust gases. That allows the engine to breathe more freely, as well as having more sound or tone since it will be less of a muffling design. The term "cat-back" means you only change the exhaust parts that are aft of the catalytic converter, keeping you clear of emissions regulations and able to pass smog tests.
As with a new air intake, performance gains are usually modest, let's say another 5 horsepower in this case. Now we're at 245.
Chip tune: $400
Modern car engines are managed by an engine control unit (ECU), a small computer that controls and monitors every parameter of what the engine does. Carmakers usually program ECUs to be conservative so the car will be reliable and smooth, but you can replace or reprogram your car's ECU with one that has more aggressive settings for throttle response, shift-point RPM and a range of other attributes. Know that such "tunes" may void your warranty, put you out of emissions compliance and even damage your engine. Still, they're rather popular and may put another 10 hp into our 2004 Matrix for a grand total of 255.
All told, we've spent about $4,200 and gained about 120 horsepower, a typical scenario for any number of modest compact cars. But most drivers will skip the turbo or supercharger and just do the air intake, exhaust, chip tune and a few-style decals and call it a day.