2004 mustang v6 3.9l exhaust

I bought the car with dual straight pipes on it. The cats and mufflers have both been deleted and there are no rear o2 sensor ports in the pipes. I need to know what I can do to bring the car up to inspection and tone it down a few decibels, all without affecting the performance much. Any suggestions?
 
I would check local salvage yards for the stock cat H pipe and the have a flowmaster, borla or whatever muffler that suits you welded onto your existing pipes. You likely will not lose any performance as the straight pipes only made it louder not faster.