You will loose some bottom end torque. But if not towing not a big deal.
I would stay with single out.
If looking for a good flowing exhaust system look at borla. Yes you will pay more but end of the day it sounds great little to no cab drone and will last the rest of the vehicles life. As there cat back exhaust are 300 series stainless steel. And all there mufflers are packed with 300 series stanless steel vs magnaflow which uses rockwool for three packing.
If you just want to add noise buy a flowmaster it really does not flow well at all and will fall apart very soon.
If you want better flowing go with magnaflow but it will drone inside the truck and basically be burnt out in a few years.
MBRP from what I hear makes some nice stuff but never dealt with there product.