I have just started to do my mod exhaust research. I noticed generic glass packs are damn cheap. Also, the purpose of modifying the OE exaust is to have less flow restrictions. What better than glass packs? Back in my younger days this is what everyone did. Why not any more?:confused:

 

bosulli,

As a fellow Tennessean, I suggest you find some people around with a sound you like. Most people I know, myself included, just get rid of the muffler and run straight pipes. You get a completely different sound than you used to with straights. The cats really tame the sound down on these trucks. Glasspacks are cheap, and they usually turn into straight pipes pretty quick. It doesn't take long to blow out the fiberglass packing inside them. Lots talk about the lost torque and I agree you do lose some. I don't notice it until I hook up to a heavy trailer. If anyone knows of a glasspack that keeps the back pressure I would like to know. Good luck with your truck, Rich.

 

So, the less you restrict the airflow out of the engine, the more HP you get, but less torque.