Just bought a 86 m1009 with a banks installed, couple q's
 

To start off, I know the 6.2 is slow, we have one here already. I just bought a 86 cucv with a banks turbo setup on it. What I am wondering is, what are the most likely points of failure, and/or where can I safely squeeze out some more power? Is 4" really worth it on the 6.2 w/ the banks kit? I can make charge piping so how about an intercooler? What about fuel stuff (injector pump, lift pump, injectors)? How about a bigger turbo? What would be first to fail from turning the boost up if it was intercooled? I have a fair amount of money to work with so any suggestion is welcome. Since I already have the banks kit I'm looking to see where I can get the most bang for my buck. Thanks for any help.

P.S. Please no "buy a cummins" comments, I'm not looking for a super fast truck, I just like the K5, but I dont want a super slow turd either.