Only way to make it louder is to punch out the muffler and it will probable sound horrible. If you want to go cheap you could always take them off and dump the exhaust but as dad as altering mufflers to sound louder/ better it's next to impossible
I have a Flowmaster American Thunder axle back exhaust and couldn't be happier, either that or the pypes dual kit, but both sound identical to me. It's loud when you want it to be and quite when your cruising. Plus it won't break your bank.
Would it be loud and sound good if I just took out the fiberglass of the muffler or should I just buy flowmasters?
You could do that or go with dual exhaust also if you wanted you could buy some gt takeoffs. My friend got a gt takeoff muffler and installed it sounds louder then before but no where as loud as duals if I where you I would go duals though because most people end up going that way :p
If you want to just change your muffler for a loud one check out flow masters super 10 series muffler it's their most agressive one!! Crazy loud on outside an hella loud on the inside! What I like is it extremely loud and only 70$