Here is why I wouldn't. Years back I had a side exhaust as you want to do. High RPM's in 3rd ready to shift 4th and the motor let go. The exhaust oiled the tires and that was the end of that car.
After I wanted a 3 1/2 exhaust with tail pipes so I dumped the 3 1/2 under the car in front of the rear but tied the tailpipes in for the aesthetics and sound coming from the rear. 2 engines later and the oil never reached the tires. This exhaust still allowed 8000 RPM's and flowed great. quiet under part throttle.