Yes, according to QS standards, 100 is the general rule of thumb.
Reference: PPAP manual – Rev 3, pg. 6&7, section I.2.2.9.2 Quality Indices
Reference: SPC Manual, pg. 31, section A.1.c.
Should the Ppk be above 1.33? Well, if we just go by the standard, a Quality Index of <1.33 doesn’t cut it. 1.33 to 1.67 acceptable but may require some improvement. > 1.67 – rock on. But ultimately it is what you and your customer agree upon.