CAnderson,
I post this is hoping for some responses so I can learn here too. Yes the 24v makes more power, but dont let them fool you into thinking its just a box and DD's. They still all buy gauges, exhausts, housings, hx40's, air intake systems, etc. to monitor things and keep the EGT's in check. Yes you can read about BIGBOB posting 450+ with his injectors and box, but dont think thats the only mods he has made.
Power:
TST Plate - Box and Boost Module
Injectors - Injectors
EGT's / Sound / Etc.
PDR HX35 - HX40
16cm housing - 16cm housing
4" exhaust - 4" exhaust
air system - air system
clutches - clutches
gauges - gauges
What I see is the 24v make more power for the similar mods, but also costs more to BOMB. A good 97-98 12v is cheaper to buy, cheaper to BOMB, but will have about 100hp less.
Personally I would keep what you got, BOMB it and be happy. Selling your 12v, buying a 24v, and them BOMBing the 24v will prolly cost you more, than just calling Piers and telling you want to go wild on your 12v. -- Now if I didnt have a 12v already, and was looking, and could afford the newer trucks, yes I would buy a 24v.