The upgraded exhaust will not have any affect on your torque curve. And in fact, you shouldn't have noticed any power increases at all. Headers by themselves wouldn't add more than five or ten horsepower to you rear wheels (Despite what the advertisement says)
And the computers are very sensitive to any modifications. When you add headers and larger exhaust, you're changing the breathing characteristics of your engine, and your computer needs to be reprogrammed to compensate for that.
Also, your O2 sensors are relocated slightly, and may be receiving different readings than they normally would on a factory system.
There's not much you can do about your situation, other than complain to your dealer if you're not satisfied with their product.
If you decide to stick with it, go to a performance tuner and ask them to reprogram your computer and dyno it for best performance.
In the future, don't believe anything a dealer says out of their mouths. And remember, a dealers job, and only motivation, is to part a person from their money, and they'll say anything they need to in order to get it done.
Jan 8, 2010 at 1:21 PM
