PARTS LIST that will get the most out of your truck while still keeping it somewhat reliable:
Supercharger Pulley: $162
S/C Snout Cutter: $110
Y- pipe: $301-469
New Intake: $400
Engine Management (URD
or AEM): $1800
Hi-Flow injectors + Harnesses: $440
7th Injector Kit: $580
New fuel pump: $150
Rods and Pistons aren't a terrible idea either: $1800
Valve Body Upgrade: $600
So as you can see there's a little bit to take on when it comes to switching down to the 2.55". If you are searching for just a bit more there are some people who have gotten away with going to the 2.7" with just the FPR mod over what you have now and are still on the TRD reflash. The mod helps maintain fuel pressure at all times.
The voice of reason tells me to tell you to bank that money and enjoy the truck for what it is. A FAST PICKUP. Take that money and put it towards a car that can actually utilize the power and put it to the ground, and as I am sure you have come to realize these trucks can't. I recently had the same thoughts as you, but after realizing all that goes into giving the truck maybe an extra 40 horse I decided it just wasn't worth it and I would turn my sights to a weekend warrior vehicle... Do what you will I just wanted to inform you.