couple thoughts ...

assuming you have the factory tow package, you already have a trans cooler so the trans should not be overheating. if you DONT have the factory tow, then you should install a cooler as soon as possible.

either way, go big or go home. it is nearly impossible to over-cool a transmission. Get a cooler with the highest GCWR rating available and look for a "plate and fin" construction, as opposed to a "tube and fin". the plate style cost more, but cool much better and consume less realestate behind the grille. factory coolers are all plate and fin types, now, for exactly this reason.

if you have room to mout one in front of the AC condenser, as opposed to strapping it right to the condenser, consider one with a built in fan. My favorite is the B&M because it comes with a thermostat and fan as a package. Derale makes a killer cooler with a fan, but you need to buy the thermostat separate. the nice thing with the t-stat and fan is it will kick on and cool the trans when you are not driving at highway speeds. backing a trailer is a trasmission's worst nightmare, and conventional coolers don't help a bit because you arent forcing air through the grille. obviously, they cost more, but doing things the best way possible always does.

Super Duty's put the trans cooler between the condenser and the radiator. the thiking here is that the engine mounted fan will draw air though the cooler all the time, negating the need for a dedicated electric fan. i would say this would be the most dificult to replicate, though. seems like a lot of work unless the provisions are already there.

as to the transmission behavior ... it is learned behavior. these transmissions have an adaptive learning strategy. that is why the reflash works for you. the only way to 'unlearn' that harsh shift is with a reflash. so they reflash it, and you continue to use it like a truck (as it should be), and it re-learns to shift like that.

if i were to guess, it is because you tow with it. if i were to guess further, i would say that the harsh 5-4 shift is only when unloaded. i would not be surprised if it feels fine with a trailer on, and feels harsh with out it. i would guess that it is learning to shift harder because you tow often. more load requires a "harder" shift to get the same "shift feel". so it is trying to achieve a specific shift "feel" and it has to harder with a load on for the driver to get that same "feel" .... not sure if that makes sense or not, but that is what i would guess is going on.

so ... how do you fix it?

i've hear nothing but positive things about 5-stars tunes. ESPECIALLY when it comes to thier trasmission tunes.

i would start by giving Mike a call. If he can help you, he will tell you.

as for the cold air and exhaust kits. do them if you like, but dont expect a huge return on investment. buy them for looks and sound if you are into that sort of thing, but buying them in hopes of them paying off in the long run is bad ju-ju in my opinion.

hopefully others who have used Mike's tunes will chime in for a 1st hand opinion.

good luck, and welcome to the forum!
keep us posted!!