Both!
I have a 6 inch lift, tires and a borla S-type. I can say that both options are fantastic but for different reasons.
Needed lift for extra ground clearance, larger tires and visual appeal. Lost a lot of gas milage doing this.
Boa to make the new size sound great and to get some performance back.
If I had to do it again I'd do exhaust first, then lift. It's less of a blow to mpg and you will enjoy driving. Seems like most trucks have level kits but a mean sounding exhaust completes the package.
But, do what you think will make you most happy with your new truck that does not do anything to warranty.
Good luck and have fun.
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