Porsche Rear Diffuser

Does anyone know who makes a carbon fiber rear diffuser which bolts on?

You can't really have true functional diffuser down there as the exhaust takes up a good portion of the rear underside. GT3 Tek has a diffuser look rear apron available.

A functional diffuser should be possible if you make a throat that is 24" wide and 16" long. This shouldn't interfere too much with the headers and allow air for cooling flow beneath the engine. You could put some 0.063 thickness aluminum angle 1.5" X 2.0" to create a funneling effect to the throat entrance as the air compresses and accelerates within. The expansion area could be 24" long and 29" wide to stay between the exhaust pipes. To flair outside the pipes and see if air extraction would improve downforce, you would need to flair to 39". The strakes would probably need to be no more than 2" from the ground to get much effect. Just a few design notes from a drawing I made. I've yet to construct it.

A functional diffuser should be possible if you make a throat that is 24" wide and 16" long. This shouldn't interfere too much with the headers and allow air for cooling flow beneath the engine. You could put some 0.063 thickness aluminum angle 1.5" X 2.0" to create a funneling effect to the throat entrance as the air compresses and accelerates within. The expansion area could be 24" long and 29" wide to stay between the exhaust pipes. To flair outside the pipes and see if air extraction would improve downforce, you would need to flair to 39". The strakes would probably need to be no more than 2" from the ground to get much effect. Just a few design notes from a drawing I made. I've yet to construct it.

I always thought a lowered 996 would look cool with one but have not seen one available.

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Are you an aerodynamicist by chance? You have a pic of the drawing? I still do not see a very practical way to do it on a regular street 996 with the m96 motor and stock exhaust(at least with the vertical strakes in place). Just from eyeing it, the engine/cats hang down a bit lower than the rest of the body work. I'm not proficient enough in aero to determine whether the rake of attack going backward will have any negative impacts. Here's a few I've seen on 996 race cars or non 996 models:

Falken RSR flat bottom:

Thank you all; there's got to be someone making these. I saw a few on the internet and one on an M3 that looked awesome.

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Sharkwerks makes the cf one you see above for 997.1 which is pretty close but won't be a bolt on like you're looking for. Oh, and I don't know if you wanna pay $3k for that, especially for a 996 just for the fuhraze effect.

AB-flug makes one http://autostyle-usa.com/?pkey=item_...ker_url=abflug http://autostyle-usa.com/?pkey=item_...ker_url=abflug http://autostyle-usa.com/?pkey=item_...BF92141310001&

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No mention of whether it was wind tunnel tested and what the measurements were. If I'm going to be spending $1500-$3k+, I'd want to make sure that this was the last mod I needed to compete in the nationals and it actually worked. Either that or if I had money up the wazoo and needed this to win national show car awards. The Sharkwerks piece was actually developed and measured in the wind tunnel. Even then, it only provides what some might feel is a minimal reward at speed vs the cost. my $.02

A true design tested part is going to run you a lot more than 3k on a Porsche. I'm sure sharkwerks tested it. It doesn't mean they went full R&D with it. If they did it would show better gains and cost more money. I would imagine wind tunnel time isn't cheap. I never went that far into fluid dynamics but ab-flug isn't low quality when it comes to body panels

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Sharkwerks tested it and have hard raw data on it. They struck a good balance between cost and being able to extract some amount of performance from it. Sure they could've gone further with the R&D but then it would only be affordable to the top tier teams. They are in the consumer business first and foremost and not in something like F1. AB Flug is a brand with a good rep and I've known them since they started but I wouldn't place my money on "style" parts if I'm gonna be paying north of $3k. Don't confuse the quality of the parts themselves with performance.

Did OP ever mention if he wanted it to be functional, or is this just a bling piece?

I interpreted as a bling piece since he said he saw one on the internet that "looked" awesome. Anyone looking to pay anything remotely close to $3k on a rear diffuser for bling on a 996 needs to have their heads examined imo. Of course there are peeps that pay up the wazoo for a carbon fiber wrapped piece so it wouldn't surprise me. I need to come up with carbon fiber lug bolts soon. I think there will be a demand if there isn't already.

$3k! WTF?