Don't know where you get your figures, but the figures in this article are exactly what Porsche claimes. Without wanting to offend you:

There is not more torque with the X51. I've even asked it in Porsche Centre Stuttgart to be sure, because I wanted to know before I did order the X51 or not. Couldn't believe it didn't have more torque, but according to Porsche it hasn't.
Torque is NOT a "staggering" 475NM! but 440, just the same as without the X51, the time given is from 0-62... Not 0-60, and it's a manual. C4S with X51 and PDK does 0-62 in 4.0 seconds. (Official Porsche figures)

Official specs:
-Optimized engine management
-Power-up from 400 to 430 hp/7500 rpm (440 Nm/5750 rpm).
-Engine bay styling with titanium-colored cover and carbon inserts
-Sportexhaust-system
-Sport Chrono Package with dynamic engine-mount
-0-100 km/h: 4,0 s with PDK (4,4 s with manual gearbox)
-Vmax.: 306 km/h with PDK (308 km/h with manual gearbox)

 

Well Suzy991, I get my figures mostly by personal research, then I enjoy comparing results in real life
Well like yourself, my curiosity lead to a trip to Germany as I simply couldnt order my car without knowing everything in it. I knew that a simple phone call or email wouldn't satisfy my hunger.
So I went to Germany and spent more than 4 hours with Porsche Engineers, in Stuttgart, then another 4 months waiting for "It" to arrive, then 3000miles on the odo to start reaping results

I don't know to whom you talked to in Stuttgart, but that person surely was more into sales than he/she is into performance.

I hope I managed to insert Porsche official X51 torque & HP chart to this message, otherwise I suggest you visit: www.porsche.com/uk/powerkit-911-carrera-s/ and sharpen your skills

475NM@7500rpm in a 991 C4S is staggering. "In Real Life" situations, the effects are simply A M A Z I N G...Unfortunately, only the very few will experience this, and the vaste majority will settle in just comparing figures, biased magazines figures

 

I'm very sorry to disappoint you but this chart clearly tells what I was saying... (I think you read it wrong)

The black lines are Torque (Nm) and the grey lines are power output (Kw) to make it more clear I put some lines on the chart because it's very easy to read that chart wrong... It happened to me the first time
If you read the chart right it says 440Nm at 5750rpm and 316Kw (429,76hp) at 7500rpm.

Personally I didn't opt for the X51 because I just thought it is too expensive for what you get. I drove a cab with the X51 package and didn't notice that much difference that would justify the 13,360 swiss francs (19,210 minus the sport chrono and PSE). (That is $21,000!!!)

Edit: to make my decision more clear... It surely is noticable, but only in high revs (above 6000). This is nice if you track the car a lot, but for daily driving it just didn't justify the exceptional price to me. If it offered more torque at low revs, I would have considered it. But there isn't any difference in low revs.

 

Been there, done that, and totally agree. If only the seat wasn't so narrow and uncomfortable for my wide-*** frame, I'd still own my beloved black beauty!

 

Tooo disappointed suze, but only on paper as in real life those figures are just ink on paper
Sure if one's driving style is moderate, why bother and pay the extra 20K
There is a trick behind those figures that I want to decipher very soon as of next week
Gonna book a day for Dyno testing (HP/Nm/Kg) and revert

 

Numbers, magazine articles, journalists' opinions and all the rest don't really capture a car's essence and how you relate to it emotionally. Both cars are excellent but not really head-to-head competitors: the 911 is a huge range of models with a huge price range of US$84K to over US$200K whereas the R8 is a narrower range of models and prices ranging from US$115K to US$190K.

The R8 is definitely more of a personal car in that it lacks the space, albeit minimal, of a 911.

Side-by-side, the 911 looks ordinary whereas the R8 is a huge attention-getter. Very different cars and very appealing in their own ways. I'm happy to have owned the MT6 R8 V10 Spyder and happy and excited about my now under construction 2014 C2S Coupe.

Both great cars with great virtues.

 

Let us know what you get from your dyno reading. I believe mine was 330ish HP-wise. There were issues with mine being a 2wd PDK. The computer didn't like that the front wheels weren't turning. So the rear wheels had to turn both sets which sucked some of the power away.

 

I'm planning to drive about 25000-30000km/yr with my car and only a small percentage of that I will be able to use the car's potential. I surely will do some track driving but not on a regular base. That's why I decided to spend that extra money on the interior, which is where I am most of the time
I don't bother if I can get to 100km/h in 4.0 or 4.1 seconds.... The extra power is very nice of course, but not at that price. For me at least....

And to be completely honest... I bought a 981 boxster S with a manual last week and I can say that, purely as a fun car, it's better than the 991.

 

The only car that I think is as eye catching now as my R8 V10 spyder is the new Boxster. Porsche has done an absolutely remarkable job of reinventing that car. It always has been a joy to drive, but now has real road presence.

I will likely be trading in my 2012 R8 spyder and Audi TT-S for the upcoming turbo S and a 981S - that would be the "best of both worlds".

I think your choice of the 981S was terrific.

 

4.0s & 4.1s difference on paper is nothing, and shouldn't be noticeable in "real life" conditions, as the difference in driving skills between 2 drivers should easily wipe away that tiny gap that costs 20K...
Truth is, that in real life conditions the difference between a normal CS and an X51 CS is humongous and cannot be wiped away by even Ayrton Senna
Once I press the gas pedal, the car pulls away from other C4S & C2S rapidly and keeps pulling until we decide to stop it...
Got a few home made vids that shows how it really feels

 

Going from a 7 speed manual transmission to a 7 speed PDK with sports pasm and sports chrono definitely gives a jolt in acceleration. The X51 power kit has a little more torque at lower rpms, a little less at mid range and a whole lot more in the upper rev range. Torque in the standard S falls off a cliff in the upper range. The torque curve in the S X51 is much more linear: no lumps, or valleys.

 

A 24% loss in power is huge!!!I think the only way to dyno the car is with a manual transmission.

 

Totally agree, of course. Each car has its own virtues and for the past two years the R8 has won my heart. But, from what I've read so far, the Turbo S may bring me back to my 40 year existence with Porsche. That will happen if the car has the "soul" that my older Porsche turbos had. With me, the subjective, emotional part of the car equation is as important as the objective component.

 

It was originally planned as an interim car while waiting for my C4S but after driving it for a week now, I'm pretty sure that I will keep the Boxster next to my C4S. As you said... Best of both worlds (allthough not a Turbo in my case of course, but a C4S as a daily driver is perfect for me)

Boxster feels like the car turns exactly around you when you enter into a corner... It's so rewarding to drive! It makes me curious about the the Ruf 3800S.... must be the perfect blend... Boxster or Cayman with a 420hp carrera S engine and transmission.

 

I have a C4S starting production next week, and decided to add the X51 Powerkit. For me, any chance to let the Porsche engineers improve on the 3.8L flat six is worth it. I look forward to the butt-dyno test when it arrives!