[MaximumSpeed]

I've heard it is illegal to have glass packs. Is that just in certain states? Is there any good reason NOT to get them (if they're not illegal, of course)? Even if they don't improve performance, they sure do add an awesome coolness factor!

[spinner]

Hmm, I've never heard of them being illegal, but if they are noisy enough to break noise ordinance laws, then I could see them being illegal in that regard. And, technically, they should improve engine power even just a little bit - it's just that they tend to be louder than conventional mufflers.

[philio]

I have never heard of glass packs before. Do you have a link or some more information about what they are and what they are used for?

[tuner]

Philio, they're basically mufflers designed so that exhaust moves straight through the center of the muffler, easing back pressure on the engine to give it more power, but generally increasing the amount of noise made. They're called "glasspacks" because fiberglass is wrapped around inside to reduce the noise as much as possible.

Here's the wikipedia:

http://en.wikipedia.org/wiki/Glasspack