Most bang for your buck as in performance? There are no performance gains with axelbacks. I can tell you from personal experience that the Roush sound great,are made great and have no drone at any RPM. They are nice at idle and scream when you want them to. At first them seemed to quiet but after a break in period they become a bit louder.
Northern Virginia Mustang Club
Silver Mustang Registry #1045
2010 Brilliant Silver 4.0 V6 Traded and will be missed
2011 Performance White Premium GT 5.0 6MT, 19" Machined Wheels, 3.73 gears, GT500 Axle-Backs, Eibach Pro Springs, Dynojet #'s 387rwhp/380 tq.