I just bought a 2007 997S and I find the power delivery quite uneven.
While accelerating there are sudden bursts of torque at certain rpms.
Is this due to variocam? It was not that pronounced in my old 996.
Driving in first and second I find it a bit irritating.

 

I have notices this too, in my 2005 C2 . . . big jump somewhere around 2800rpm (not always at the same place - and if it does it in 1st not necessarily in second ???); then great power to maybe 4500 then it kind of flattens out or drops - this seems to follow the power curves in the manual.

Seems to be less dramtic in full throttle than in 1/4 to 1/2 throttle.

I plan on asking when I have the 20K services done soon.

 

From my experience with 911 engines, I would say that it is simply coming on the cam. It's very normal. Years ago it started at around 4000 RPM and grew until you were coming up on redline. With the larger displacement engines they are broadening the torque available further so it is very possible that it will start to come on around 3000 rpm.

Take a look at the engine torque and HP diagrams that are made available for each engine in Porsche literature. They have been providing these since day one. They should visually reinforce what you are experiencing.

 

There are definitely some weird surges below 3000 rpm. It's annoying.