How about removing the tail pipes and adding extensions from the muffs to make side pipes exit in front of the rear tires like the T/A Cahllengers and AAR Cudas have
I had a set up like that on my BB Dart, short 2.5 O.D. pipe from the fenderwell headers to the early Corviar Turbo muffs and then around 20 inches of 2.5 tail pipes out of the muffs and bent out at 45 degrees to the rocker panels in front of the rear tires, that work well They where easy to remove at the track and they didn't weigh a bunch either