lol.
They also say they'd expect it to reach 280hp!
It's up to you bud, take the advice of a motoring journalist who drove the car for a day at most.
-or-
Listen to the knowledge/advice we've gained from owning the car. Myself for over 3 years, lgee hits the track in his on a regular basis, kranzy is a research machine, budgie would marry attesa's if it were legal.
I know who I'd be listening too.
Having said that... I ran 15psi for about a year on my t25 before chucking on a t28. Recently did a compression test and all was dandy.
With the t28 i'd reccomend no more then 10psi to be safe, I run 12psi on mine with no ill affects yet. I think I recall lgee was able to goto 13psi on a t28bb before it started leaning out. You'll notice the car is a heap faster on 10psi anyway so it should suffice for a bit.