Custom tune needed for minor exhaust upgrade?

[idencker]

I have the Edge Evo now and plan on buying a couple custom tunes in the very short term future. My question is, I have also thought about upgrading the exhaust a bit and wondered if I should wait to do the custom tune until after the exhaust work. The most I would do is a SI/SO exhaust from MBRP or Magnaflow but I have also thought about just swapping the stock muffler for something that has a bit of rumble. Any and all input is greatly appreciated.

I tow 5000 lbs. almost every weekend in the spring/summer/fall. I also know that with my CAI that I am probably running pretty lean right now so I want to remedy that asap too.

2004 F-150 SCREW 5.4 4x4 Lariat 72K Black
Edge Evo
275/70/18 Michelin LTX A/T2
K&N CAI 57-2556 - (plan to sell and go back to Gotts mod)
E-Fan from Mark 8, FAL controller 31165-VSC
2" front leveling lift
2x10" Fosgate subs under back seat
2x amps behind rear seat
6x8's in all doors