Are gl packs worth it?

Hi...I have a 96 Ford Probe SE (2.0) I know by all means this car is not fast or anything but i just want it to sound a little nicer without spending to much money since its not worth it. I was just wondering if gl packs actually work and will give me a little better sound than stock or if they are just pointless. Also if anyone knows if they are illegal in PA or not that would help me to...thank you