To my knowledge the only LTs that work on an auto are MAC, Kooks, and Hooker.
MAC being the cheapest
Kooks.....had a set priced today. $1100 for the headers and off road X. HIGH quality stuff though......worth the $$.
Hookers LTs are about $800 I think for just the headers.
MAC LT's, love them, but have a crappy hts coating and will rust at collectors. when i baught them they did not offer ceramic coating. If I could go back I would get them ceramic coated.
When I put mine on I put it on with the MAC o/r H pipe and kept the stock mufflers. It sounded mean! real deep and more solid than just a catback. Then I welded in magnapacks and dumped it after the mufflers, havn't heard a mustang around hear, let alone another muscle car, as loud and as good as mine. It sounds like I got a aftermarket cam in it and I don't at idle its lopy.