[Torch]

I used to have a 77 F-250 with 2.5 inch dual exhaust with four foot long glass packs then eventually exited out the sides of the truck behind the rear wheels, the truck was literally in the exhaust shop ALL DAY LONG but by the time it was done the truck had a very quiet mellow sound to it with a nice rasp when you floored it.

But as the years went by and the glass packs wore out it became rather loud, that is just the way glass packs are.

Well, to answer your question, the longer you make the pipes the deeper of tone they will resonate at, the lower the pitch you can get them the less annoying they will be, and the further away you can get the exhaust gases from you the better off you will be.