why did you put in a new engine?
straight pipes ? physically straight or no cat no muffler straight?
take the cat out and put in a high flow cat if you need emissions, if not put in an off road pipe.
what companies have you been looking for headers from? hooker makes the best long tubes without emissions, make sure you get the jet hot coated.
personally if i was you and i was doing the whole exhaust at the same time i would put in true duals. that would mean that you need to buy a different panhard bar (bmr makes them) so you can run the exhaust correctly
if you have any more questions let us know