Your turbo has a 1.15 A/R exhaust housing instead of the standard .84 A/R that you see in pickups. This means that your exhaust vents more freely, which in turn keeps your exhaust temperatures down. This is almost required in vans with the 7.3 due to the fact that there is no room for an intercooler to help keep the exhaust temps under control. The downside is that your turbo will spool up slower and produce less psi overall. But, with the proper mods, your turbo will more than keep up with the .84 version.
I too am looking into ways to increase efficiency. The first easiest step would probably be to invest in a good performance chip (DP tuner) and 4" exhaust. With that your going to want invest in a pyrometer to make sure you do not melt your turbo/valves/pistons. After that there is probably not much more you can do without needing to beef up your tranny. Brian's Truck Shop and John Woods are the 2 most popular places on enthusiest forums for making bulletproof transmissions. After that, stage 2 injectors, turbo mods, and possibly water/methanol injection are other great ways to increase efficiency.
Last edited by Xphobe; 08-13-2010 at 08:09 AM.