Filter back will do nothing but looks. IMHO the dual tips are ugly so it's worth it. Depending on which one you get, often they are non-upgradeable to a delete and you just start over.
If'n you aren't going to delete, just stick with the canned H&S tunes. Good for 50hp (on the dyno) and 1mpg.
I tried the KEM Green tunes and had to take it off due to so many problems. First try bricked the Minimax. KEM said it wasn't their fault/problem and would only send another card (H&S took care of me.) It had horrible turbo oscillation under light loads. Crazy trans tuning, very hard, missed shifts, flairs, just about undriveable and I really thought it would break the truck it was so harsh. Not to mention, they were claiming 500RWHP and when I dynoed the KEM tunes they were weaker than the stock H&S everywhere but a little bit of torque in one small spot. Fuel mileage on the lie-o-meter was great, but a hand calculation revealed that the KEM tunes did worse than the canned H&S.
For me, it was a waste of time and $400 ($300 for the tune and $100 for the dyno.) The KEM tunes are NON refundable and NON transferable. Once you buy it, you've spent your $. Regardless of if it works or not.
I think most everyone who is new to Ford/6.7/Diesel wants to keep the truck w/ the DPF.
Most everyone who has experience with the 6.4 or prior models wants to delete the truck...
delete pros: better power, better mpg, better for the engine, sounds a lot meaner,
delete cons: it's a warranty voider, it will fail an emission test, louder, black smoke
IMHO you should get a minimax and tune it, drive it for a while, eventually you'll want to delete and you need the MM anyway to do that. One thing to consider though is that a Street Tuner is easy to buy (can't delete) and the Race Tuners are getting harder and harder to get and they are usually pretty pricy. So if you are satisfied with what you can do with the DPF on stuff a Street Tuner is easy to find.