WRONNNGGG!!!
The purpose of emission control is to make the car as efficient as possible so that the fuel burnt will give the maximum output. When the vehicle runs at maximum efficiency the exhaust gases consists only of waste. The cat deals with the exhaust gases reducing the toxicity and quantity of it.

Older cars that did not have cats were less efficient and had lower power outputs. Remember the V8's that produced 130kW. The 2.3 litre SAAB produces 184 kW.

Can Byron please explain further.

Nai, You are absolutely wrong.

The purpose of emission control is to reduce emissions. Do you really think that when EGR routes some of the exhaust back into the engine that your engine makes more power or uses gas more efficiently? That a catalytic converter has a higher flow rate than a straight pipe? The reason emission control systems have less of an impact today is that engineers make better emission control systems that have less of an impact on the engine performance. Can emission control systems get better? Yes, but at a higher cost that is not feasible from a production point of view.

BTW, the reason new cars make more power is due to advances made in fuel delivery, engine monitoring, cooling systems, ... Engines today run hotter, atomizing the fuel for faster more complete burning, ...

If you want to discuss, make your argument, produce your supporting facts, and I will offer my counter arguments with technical data, then let the forum decide.

Nito

That's what I figured. Race cars dont have any emmission controls in order to get more power. Just straight pipe.

Ynot,

Please don't think that by removing your cat, you will free up your exhaust. The primary constriction is the exhaust manifold, followed by the small diameter exhaust pipe, and a tie between the bends in the exhaust pipe (over the axle vs under the axle) vs the cat. If I am wrong, please correct me. BTW, if you want to be street legal, they have high performance cats on the market.

Also note that your exhaust pipe diameter should be roughly based on your engine output. So if you go to large, you will actually lose hp.

Nito

I purchased a 2005 AWD used about 6 months ago.
I'm getting 21mpg average.
For a 3800 lb 4WD vehicle, thats quite good.

I keep it under 65MPH on the highway, don't gun it from a start,
and use the cruise control wherever possible.
Keep a close watch on tire pressure.

Good luck
Rick

after owning this car for more than a year, i can say in confidence its better than many other similar in gas consumption. even its better than 2 liter rivals.