Ok, I'm pretty sick of hearing my Z brothers spout the same old BS about turbo's, so I'm gonna see what you guys have to say since most of you have more experience.

Garret T3 turbo, stock turbo on my 300ZX. What is the MAXIMUM boost it can actually handle?

I've heard 15PSI, 19PSI, and here lately 25PSI, 30PSI, and even 48PSI! I personally think 19 PSI, but have no factual or logical reason, just guessing. I highly doubt it's 20+, else why would you need a bigger turbo? (Barring spooling speeds, lag, etc.)

Now I've run 19PSI on it for a few seconds with no detonation, but that's hardly a good basis for thinking the turbo can take it or likes it. So please, if you have T3 experience, chime in with your information.

 

Depends on the trim.
A t3 60-1 can handle more boost then a t3 turbo with an ar of .42.
Just because it will produce boost that high (say 20psi) doesn't mean it's good boost.
As the turbo gets out of it's peak efficiency range it heats the charge air up which has an adverse effect on power production.So you may be making 20psi of boost but your making the same amount of power as you would at say 16psi.Thus rendering the extra 4psi pointless...
My guess would be probably about 15psi...