[nonovurbizniz]

You have two mufflers??? I'd definatly like to see pics
which exhaust is this on which model car.

even then you'll only loose exit velocity not back pressure. the back pressure is created way higher up in the exhaust system. in the header or cat. if you have an aftermarket header and cat then it might start to cause some loss of backpressure but I can't imagine it being enough of a loss to cause problems.