High-Performance Mufflers

I own a 97 Caddy Eldorado. I am planning on installing high-performance mufflers. 1, which will give better results...Vortex High-Performance Exhaust Mufflers (www.vortexexhausts.com) or Aero-Turbine Exhaust Mufflers (www.aero-turbine.com)? 2, how much of an increase in fuel economy should I expect? Thanks in advance.

What kind of results are you wanting? Power, sound? More than likely you wont notice an increase or decrease in fuel economy.