If you're budget is $600 and you want something you can bolt-on so you can possibly remove it for resale I'd go with Magnaflow part #
16580. It's the comp series Cat-Back which utilizes a resonated x-pipe and it's muffler delete out back with 5" tips! It is just over your budget for a full cat-back that is made in the USA and has a lifetime warranty!
With factory exhaust manifolds and converters this system sounds awesome! The tru resonated x-pipe makes a large difference is tone quality as well as performance which you wouldn't get with the axle-back.
If sound is the main driver I'd suggest Magnaflow part #
16582 which is the Comp Series Axle-Back and our price is a couple hundred below your budget on that system, you could even remove the factory H-Pipe and resonators and use Magnaflow part # 11386 but at that point I'd go cat-back.
Please feel free to call, email or PM me anytime with questions. Have a good one and good LUCK!
Kind regards,