well I think the rotofab intake shines becasue it is no tune. It also seems to produce as much power as the intakes that require tune.
as far as exhaust sound is kind of a preference.
I preffer corsa to magnaflow hands down. all 304 construction and just sound crazy at WOT has no drone. not crazy about the sound at idle. Magnaflow uses 409 pipe and I just don't like the sound personally and it also has drone.
now with the factory catback being dual mode I think midepipe our headers are a way better place to spend the $$$ though on this praticular car to sart with.
the factory exhaust does not have resonators or anthing. you run a race cats or off road pipe it will sound good.
on the flip side you can get good money out of the factory catback towards on of the other kits.
also take a listen to the stainless works chambered system I presonally think it sounded better than magnaflow or corsa.
2013 Megacab 8" lift 38"mt's