Easiest thing would be to change your axle backs. Since you took out everything in the middle... if you went with Solos, it should be pretty loud.
I agree with Jova though. If you go to a louder muffler (or no muffler in the case of Solos), you're likely to get a bunch of unwanted noise without having those resonators. The fix there would be to order a fresh cat-back of your choosing.
2009 PBM GT
Under the Knife Again
Wiseco Pistons, K1 Rods, Johnson Lifters, BLP Keep Hatin' PDS Cam, Roto-Fab, BLP Ported Intake and Throttle Body, Kooks 1-7/8 long tubes, XForce Varex Catback, ZL1 Converter, Camaro Trans Pan/Filter, GXP Brembos
Breyton GTS-AV Wheels, 6k HIDs, Holden Steering Wheel and Paddle Shifters, Eibach Springs, 35% Tint
Tuned by Day Tuning