Depends on a few factors.
Stainless steel or aluminized?
Main brand or off brand muffler?
Pre-fabricated or custom install?
Tips or no tips, and how fancy?
Bottomline is that you should be able to go to a reputable local muffler shop and have a high quality cat-back custom dual exhaust added for $400 to $600.
Check out this
tundra exhaust article for more info and some good tips.
