A customer of mine wrote up a great guide to assist with the install of the 718 header/manifold. He approved me posting this here in the hopes that it may help some folks in the future.
This Lemon service manual here was a huge help: LINK
1. Factory Manifold Removal Is More Complicated Than It Looks
Removal of the factory manifold is significantly more complicated than it initially appears.
There is a 13 mm supporting M8 bolt that connects to the turbo mounting bracket through the fourth hole on the manifold. This bolt is extremely fiddly because it is located directly under the cold-side turbo outlet and in front of the wastegate control.
The bolt needs to be slowly worked out ahead of all the other bolts, and then the nuts can be removed from the turbo and manifold studs.
This bolt is documented in the service manual, but it was definitely a pain to remove. When reinstalling it, access is extremely limited, making it very difficult to get a torque wrench on it to ensure it is tightened to the specified 22 Nm.
2. The Factory Manifold Studs Must Be Removed
The studs on both the manifold and turbo must be backed out in order to remove the factory manifold, then reinstalled with the new manifold in place.
The manifold mounting flange actually sits between the turbo housing and the turbo mounting bracket. There is not enough clearance or wiggle room to remove the manifold without either removing all three studs or removing the turbo.
I chose to remove the studs rather than the turbo.
3. Turbo Stud Length Is Important
The stud on the turbo is longer than the factory manifold studs. I did not measure the difference, but by eyeball it appeared to be approximately 6 to 8 mm.
The Top Gear manifold mounting flange is also slightly wider than the factory flange. Because of this, I don’t think you could successfully reuse the factory manifold studs in the Top Gear manifold locations and still have enough exposed thread to install the nuts properly.
This is most likely what has tripped up other installers in the past.
I used three of the factory turbo studs, part number 90008105901, in all three locations. This provided enough thread engagement to use the two-nut method to install the studs and then torque them down.
One note: the stud location on the turbo is very tight to access. It is doable, but requires patience.
4. Remove the Downpipe
All of this work is much easier with the downpipe out of the way.
I would assume the downpipe needs to come off to perform this work unless you have really small hands.
5. Pay Attention to Manifold Clearance and Heat Wrap if using
The clearance and tolerances of the manifold piping are different from the factory manifold. The new manifold piping sits farther away from the oil pan and lower than the factory manifold.
This results in some very tight clearances.
I found that my heat wrapping was interfering with my ability to get the manifold seated properly, and it also made bolt #2 difficult to get properly threaded.
Removing a section of the heat wrapping helped, but the bolt still needed to be over-torqued compared with the factory requirement in order to get it flush against the manifold and gasket.
6. Bolts #8 and #10 Are Difficult to Access
The bolts labeled #8 and #10 below were very difficult to access and ratchet down.
For bolt #10 specifically, I needed to use a set of vice grips to get the bolt started and positioned low enough to fit an E12 wrench, followed by a 1/4″ E12 socket, so I could torque it down to specification.
The access felt like a design decision that may have been made on a 3D computer model without being fully tested on the vehicle. A little more length or a slightly different angle on the piping in the other direction would have made this significantly easier.
Useful Part Numbers
| Part Number | Description | Quantity | Source |
| 999-073-589-01 | Exhaust manifold bolt | 12 | Porsche Columbus |
| 982-251-235 | Manifold gasket | 2 | FCP Euro |
| PAF-007-634 | Exhaust manifold nut, for turbo studs | 3 | Pelican Parts |
| 982-251-616 | Catalytic converter clamp | 1 | Pelican Parts |
| PAB-253-115-A | Converter & pipe gasket, turbo to catalytic converter | 1 | Pelican Parts |
| 0PC-145-039 | Turbocharger gasket, manifold to turbo | 1 | FCP Euro |
| 999-061-409-01 | Turbocharger stud | 2 required for the new manifold, plus 1 spare in case the turbo-mounted stud fails during nut extraction | FCP Euro |
Additional Notes on Parts
999-073-589-01: Exhaust manifold bolts — quantity 12. I believe these must be purchased in packs of five. I ordered mine from Porsche Columbus.
PAF-007-634: Exhaust manifold nuts for the turbo studs — quantity 3. I purchased six just in case.
999-061-409-01: Turbocharger studs — two are needed for the new manifold, with one additional stud recommended as a spare in case the turbo-mounted stud fails during nut extraction. I ordered five total.