Chuck,
I currently have 76XX miles on my car with the turbo system over 2 1/2 years. All very hard miles, if anyone knows me(or has seen my vidoes
) I do not get the SVX out for a saturday stroll to get groceries.
I do however as you stated have a lower milage motor in my car. a perfectly running car should be the first step in anyones plunge to FI. You will have ghosts in the closet on a 150K mile motor for almost certainty. Best bet is to at the very least make sure PCV valves, compression, and all of the vacuum system is copesetic. Irreguardless of mileage we are all working with something 12 or so years old, so like Chuck said be sure you are not working from behind the line of scrimmage.
When an intercooler becomes a neccestity has EVERYTHING to do with the temperate in the engine as stated below and nothing to do with a set boost level. You and I are both running to small of a compressor housing (yours looks to be a hybrid ~.50 trim impeller housing on a .63 a/r turbine) for peak temperates in the combustion chamber at any boost level. As you stated, the intercooler does not care how much pressure you are running. If you were blowing 5psi of 250 degree air at 30,000 shaft RPMS into the engine(high heat energy, low density), the intercooler will drop that temp substantially and will drop the charge pressure slightly, but increase the charge density greatly. I can touch my intercooler piping after a beat run, anywhere after and even right next to the motor. I am almost certain that would be a third degree burn on an un-intercooled charge pipe, say a boost tube a foot down stream of the impeller. Heat broke the ring lands on your motor. above 7 or so psi of properlly dense air, you begin to work outside of the tensile pressure offsets that a pressurized charge benefits the bottom end. But i think i have rambled enough.
Anyway around it, the built motor would be the best bet for anyone wanting to make big reliable power. Isnt it always
I will the drive the car as is with maybe a bit larger turbo, but I will not be dumping into the built motor. Its not worth the amount of time and money to me.