Many thanks to Cattman for a great installation DIY. I've transcribed his MS Word doc into a post, and will link it to the 997 DIY thread.

Please positive rep him for sharing this with us.

CATTMAN’s DIY for installing aftermarket Plenum in Porsche 997:

Tools: [picture 1]
· Hose pick set
· Screwdriver (varies, some need Standard, others need Phillips head)
· 8mm 12 point wrench
· 11mm socket (with ratchet handle).
· “E10 external Torx” socket, aka “female Torx” socket (with ratchet handle). If you don’t have or can't find this unique socket, a 8mm 12 point wrench will just as well, and won’t strip the bolts.

Area of focus: [picture 2]
The diagram below details the area you will work on to install the after market plenum.

Step 1: Remove hose to expose throttle body[picture 3]
Below, I am pointing to the top of the air intake hose where air comes from the OEM air box, and into the throttle body. It is connected to the throttle body by a single hose clamp, that I am pointing to. Using a screwdriver, loosen the clamp enough so that it slides down the hose, and out of the way. With the clamp out of the way, simply shift the hose to the side, off the mouth of the throttle body.

Step 2: Remove throttle body [picture 4]
Disconnect the black wiring harness, seen in the picture below located at the top of the throttle body. To disconnect it, squeeze the top and bottom, while pulling it out of its connector, meaning toward the left/driver’s side. It’s pretty intuitive if you look closely at it.

Next, remove the 4 bolts which hold the throttle body to the OEM plenum. In the picture above, I am pointing to one of the 4 bolts. There is 1 bolt on each corner of the unit. On my car, these 4 bolts were odd sized E10 “female Torx” bolts. If you can’t find an E10 socket, you can safely use an 8mm, 12 point wrench. You should now have the throttle body removed.

Step 3: Remove plenum [picture 5]
The picture above is showing an after market unit, but that makes no difference in these instructions. Your first task is to remove the driver’s side crankcase ventilation house, seen in the upper left of this picture - it’s a black, ribbed plastic hose, about 1 inch thick. CAUTION: this hose is very brittle, and can easily snap! To disconnect it, squeeze the outer ring of the unit where it attaches, and gently pull the hose off to the left/ driver’s side.

With clear access to the OEM plenum, use a screwdriver to loosen the 4 hose clamps (2 on each side of the plenum) which snug the black rubber sleeves over the ends of the plenum and the air distributor. Once loose, move the rubber sleeves as far toward the outside as you can, using hose picks carefully as necessary. Slide the plenum back and forth in the rubber sleeves until you can wriggle it out, freeing it from the vehicle.

Installing an after market plenum, is as simple as reversing these steps. The hardest part is getting the new plenum into the existing black rubbers sleeves so that it fits perfectly without a gap on either side; it’s got to be perfect, as you don’t want an air leak.

Hope that’s helpful!
CATTMAN

 

Another thanks...just added to the link

https://www.6speedonline.com/forums/...ml#post2769490