Hello double t. That's cool that you are upgrading your exhaust. I wish I could give you some advise on the glass pack and how to get the best performance and sound from it, but I don't have any experience with that type of muffler, nor with the 3.4 V6. I would suggest asking your questions over on the "Toyota SUV and truck tech section"
https://www.yotatech.com/forums/f2/ and you will probably get some better advice. Sorry I couldn't be of more help to you, good luck with your project!