Effects of a cat-back system

[97Chevyguy]

With the stock exhaust system on my truck, I was able to just put the pedal to the floor and I would be able to peel.  Now that I have a cat-back system on the truck I found that you can't peel when you put the pedal to the floor.  Has the cat-back system caused a decrease in horsepower and/or torque or is there another explanation?

[Shaners]

More than likely you have actually gained some power.  The problem with aftermarket exhausts is that although they create more HP, they move the torque and HP numbers further up in the power curve which leaves your truck a little "flat" on the bottom end.

 

The factory exhaust is a "tuned" exhaust, and the back pressure it has keeps the torque more available at lower RPM's.