Minimum Vacuum Pressure for Monte Carlo Dual Diaphragm

[gnonyx]

I have read some are using 87-87 Monte Carlo Dual Diaphragm Brake Booster to replace the PowerMaster.
 According to this Monte Carlo site the admin. wrote:
 "For the brake booster to operate at peak performance, engine vacuum should be ideally at 18 inches"
 http://www.montecarloss.com/community/ubbthreads.php?ubb=showflat&Number=757283#Post757283
 I don't know what everyone vacuum is, but on my TR I have 18psi.
 With that being said, can I still use the Monte Carlo Dual Diaphragm Brake Booster?
 Also I have read if you have some mods done on your engine the vacuum could be less than 18 psi, is this a true statement?

[earlbrown]

when you're cruising along at 50 and lift the throttle the vacuum will be waaaaaay higher than 18 inches.   I'm sure it'll work just fine.

[Steve Wood]

that is ideal vacuum.  It will work well down to about 12 psi in my experience altho the reserve will be less at that level

[gnonyx]

Thank you guys, right I don't have an issue with the PowerMaster, and I do have a spare in hand, yet I read a lot of stories of the PowerMaster stop functioning when you really need to stop. I already replaced the accumulator ball since I still had the all black type. I do periodically check it with a Kent Moore J-35126 Pressure Test Gauge, but nothing has a guarantee.
I'll soon be changing over to the Vacuum type.