I drove my factory stock, air-to-air intercooled MR2 Turbo for 7 years and 128,000 miles w/o an engine or turbo failure and was still redlining it the day I traded. However, it was the Toyota GTE-SE(SPL?) 2.0 liter racing block with forged internals and low CR. Dan Gurney later used the same block in GTP racing and was running 22-24 psi and getting 700+hp! His CR was about 7.0:1 and everything in the motor was forged, including the block.

My point is you will spend lots of money FIing the Z. Lowering the CR and building up the block will be expensive, keeping the high CR and keeping the boost low will be expensive. Either path you take will lower the life expectancy of your motor and the rest of the drivetrain. Asking how long you can go really fast with after market FI systems is a crap shoot. The bottom line is there are too many factors to say how long you have before bad things happen.

My MR2 T drivetrain was fully warranted by Toyota for 5 years or 60,000 miles and I put 68,000 miles more on w/o a failure. I was very, very careful and I didn't race on a track or a street, just drove fast on highways and byways with low traffic and never got a bad tank of gas or other anomaly that could turn my engine into scrap. Do you feel lucky? I would always keep my wallet closeby, you will need it.

 

Simply replacing your factory internals (Rods and Pistons)
with Forged equivalents will not extend long term durability (unless you have a detonation issue from the factory, which you shouldn't). Forged pistons have the slight side effect of expanding at a larger rate differential WRT to the sleeves when compared to the typical factory castings. This can lead to cylinder scuffing at low operating temperatures. So if you use forged pistons on a daily driver take the extra minute or two to let it warm up before letting 'er rip. Racers know this , Joe the daily driver useually doesn't. This input was extracted from the Corky Bell book "Maximum Boost"..