KresoF1:
acrobat:
reginos:
In Sport Plus Manual mode my car hits the rev limiter. Is the 991 any different
According to Sport Auto (Supertest) and AutoBild yes, it shifts up at 7600 rpm. 
Are you sure? Since I have that issue of Sport Auto(Heft 12/2011) in front of me right now and after re-reading the Supertest twice there is no mention that PDK shifts up automatically in Sport Plus M mode. In fact reginos is 100% right when he claims that in Sport Plus M mode you can hit limiter. Same is with all PDK 981 and 991 models. Maybe you are talking about Sport Plus D mode? Since you can use paddles when the lever is in D mode. To switch to full M mode you need to put lever in to M mode also.
I know what's the difference between D- and M-mode. 
Horst von Saurma: "Automatisches Hochschalten am Drehzahllimit und Kick-Down-Funktion - das sind die einzigen Indizien seitens des PDK-Getriebes, die dem Geist der reinen Sportlichkeit widersprechen"
AutoBild: "Die Schaltwippen kann der Fahrer vergessen, das PDK schaltet bei Maximaldrehzahl selbstständig hoch, bei Kickdown ebenso selbstständig zurück. Kann man mögen, muss man aber nicht."
I think both authors know about the M-mode, so it's obvious to me that they are talking about both modes at once.
But since I never drove a 991, the truth can be the opposite. 