[Christ]

Originally Posted by Peter7307

This mod is very common with the European owners of Vectra and Astra cars.
the "doof , doof" baseball cap backwards wearing brigade.

It is generally known as the "three pipe mod" when all three resonators are removed and the the intake pipe sealed.

The upside is...
1) it makes more noise ,
2) there are bragging rights
("I've done the three pipe mod you know" - ie "I worked out with a hacksaw and a roll of duct tape what the engineers at GM with dynomometer cells and Cray super computers couldn't")
3) weight reduction !

The downside is...
1) it makes more noise , and
2) it makes LESS power.

GM have actually worked all this out before the put the car in the show room!

Keep in mind too EVERY bit of plastic costs money to make and install.
If it is there it is most likely there for a good reason.

Pete.

The reason is NVH. Noise, Vibration, Harshness. It has little if anything to do with power, since the resonators are usually placed in such a way that they don't restrict airflow at all, only allowing sonic waves a place to reflect into each other, canceling themselves out.

You're right, GM has worked this stuff out, and they've turned it, like everything else, into a compromise. They spend the pennies to win the dollars, my friend. Many people won't buy a car that makes noise under the hood. That would be perceived as something "wrong" with the car by most.