Get long tube headers with ORY (no cats) and you your current exhaust set up might end up too loud. Many guys on here run 2 mufflers in sequence to quiet down the exhaust after headers with ORY is installed.
As mentioned just above, straight pipes and glasspacks are obnoxious...and in my opinion sound like total crap. But this is preference, I like a nice loud "toned" exhaust not raw and raspy.
How long is your muffler now? The smaller, usually the louder. Also depends on chambers if you have a chambered muffler...1 being the loudes (ie: cherrybomb extreme or flowmaster racemuffler).