Old post I know. But some relevant information.
What I did and was cheap, no electronics.
My setup is 3" Taipan-XP Exhaust, Aluminium 2 core radiator with 1.3 BAR cap, Viscous fan that WORKS! and Safari Snorkel. That's it. No other trickery
Stock standard engine.
Fit a boost tee valve that intercepts the wastegate and compressor housing outlets. I used the 'Turbosmart Manual Boost Tee'. A hell off a crap job, but not too hard, can be done in 3 hours or so.
Then, instead of getting an electronic FCD to intercept the signal to the ECU, find the MAP sensor and clamp the vacuum line going to it from the intake manifold. It involves a bit of experimentation. Too much clamp equals too little fuel then no boost, no clamp and it hits boost cut at 15PSI. Then it just sucks, like hitting a brick wall effect due to no more fuel. You could spend the money and buy the 'Turbosmart Pneumatic FCD', but it does exactly the same thing! I used to use a small vice-grip to get the perfect AFR and EGT, and now I just use a small hose clamp to clamp the vacuum line going to the factory MAP sensor.
I run mine @ 20PSI using this method, and yes, you do get extra power! The injectors and injector pump has no problem supplying the fuel. No need for an expensive aftermarket ECU unless you want ultimate control. It provides more than enough fuel this method at 20PSI for a heck of a lot of extra power, runs cooler so no crack head future and that CT12B sounds sweet as above 15PSI. I have no intercooler so I wouldn't go above 20PSI, if you have an intercooler the 1KZ will easily handle 25PSI +, but get a higher flowing fuel pump to maintain that fuel. Too much boost can't hurt the engine, too much fuel can!
I have plenty of experience with CT12A's and B's from my 1JZ, 2JZ days. They won't blow up! just make sure you have at least a 3" exhaust system, this includes a 3" dump, and a clean free flowing air intake ie. a snorkel. Factory paper air filter is fine and advised.
End result, EGT's are lower, no smoke, it pulls a chipped D4D for dead! As a test there's a great big uphill near where I live. At factory boost of 10PSI in 5th gear I used to get up to 620°C and 100km/h, now I get 480°C and 130km/h. Results speak for themselves I think.
So there you go, a bit of MAP sensor trickery manual style, and BOOST!
As for head cracking issues, the problem is whole array of things yes, but the main culprit is the viscous fan! Get that sorted! Cool water temps and low EGT's = good head for life!
BTW, my engine is at 322 000kms. Only replacement so far was the starter motor and that crappy Toyota radiator.