Back from the depths of reality and other more pressing automotive projects with a years worth of experience with the turbo swap.

When I first did the swap I stuck with the completely stock 88 Montero bottom end and just dropped a Starion head on it but didn't use an intercooler. Running 7 psi on 91 octane things were good unless the weather turned warm or I stayed in the turbo too long, then I started having detonation problems between 3 inches vaccum and 1 psi. Growing tired of dancing around this throttle range, I swapped motors with my 87 Starion. My Starion's motor has been worked over so I drove around running 15 psi on the thing with 91 octane, still non-IC'd, without a care in the world until I noticed how little gas milage I was getting. Swapped the motors once more, so the Starion motor is in the Starion and the Monty motor is in the Monty. Re-gained my lost 3-4mpg as well as my detonation problems.

Long story short: If you're going turbo, make sure you have an intercooler to go with it.