Exhaust Cut out with spring loaded rain cap?
Running exhaust cut outs is bad for low speed performance and only good if your running wide open. So to improve low end torque could you use a exhaust rain cap modified with a spring to proved back pressure at take off and then open as you go faster?
09 G6 GT 3.5 Flex Fuel Street Edition DIY Cold Air intake W/ 6" Spectre Cone filter moved into Fender W/ 3 pieces of Spectre 3" Chrome Modular Air Intake Tubing, "Ram Air" from Drilled grill and 6x6 Splash Shield Air Inlet Expansion, LoJack Protected, Reso delete, Glass Pak Muffler to a Side Exit with a Gibson Chrome Box Tip Exhaust Tip, Red Dome & Reading LEDs, Lloyd RubberTite Cargo Liners, Rubber Interior Mats, Tint, Intake Pipe Heat Soak Protection - Silicon Spray and Heat Wrap.
Future: Tune, Dual Side Exit Pipes, Red Caliper Paint, Exhaust Cut Out, Cross Drilled and Slotted Rotors and Red Stuff Brake Pad upgrade, Cabin Air filter, Radar....