It looks to me like he just had his exhaust routed out the side and cut out his stock ground effects on that Z28. Since those cars have just a single pipe setup from the cat-back he probably had a custom dual exhaust made and had that routed out the sides since it is hard to get two pipes out of the back of those cars. I had a dual exhaust on my previous car, a 2002 Z28, and the guys who did it routed the pipes under the rear axle...let's just say there wasn't a speedbump in the world that I could get over