How much would dual exhaust cost me for my 86' Z?

 

first off the 300zx wether it be turbo or n/a was never meant to be dual exhuast but anything is possible.the thing is on the underside of the car theres not alot of space for another pipe i think the only way to do it would be to add more pipe after the muffler and run it to the otherside of the car lol but that seems kinda ricer-ish.