Both Tony (Manifold and Valve Covers) and John have great write-ups on removal and refinishing of these parts.  I have chosen easier path - I have had them removed (not cheap!).

What Else To Do At This Time

With Intake Manifold removed, the following  is what I had done at the same time:

• Idle Stabilizer Valve
• Idle "flappy valve" (intake air tuner flap),
• "flappy" valve bearing,
• Knock sensors,
• Fuel rails insulation,
• Fuel Injectors cleaning (was not sure about replacement due to differences between reasonably priced Ford injectors vs. unaffordable 982 injectors),
• Re-finishing other parts:
• Control cables bracket,
• Thermostat housing,
• Cooling water outlet elbow, and
• Valve covers.

• Powder Coating
• Cons -
• It is referred to as "crap shoot" - whatever come out is what one gets.  Apparently there no control of the shooting process.  To change the results old surface needs to be stripped before new coat may be re-sprayed.  Results may still be not to one's liking;
• Color selection is limited to pre made available choices (no mixing and matching).
  
• Pros -
  
• HIGH DURABILITY!!!  This is very important advantage.  I got my manifold side covers damaged during simple bolting.  Mechanic has used metal washers directly over the newly painted surface and paint flaked on all bolt holes!  It took them 3 holes to realize that they were destroying my parts!
• Paint
  
• Cons -
•  very fragile finish (learned form my own experience).
  
• Pros -
  
• complete control of the process to assure high quality finish,
• unlimited colors mixing and matching.
  

Pricing will very depending where one wants to have the job done.  Often, with shipping costs included, one can find reputable shop that is much less expensive that the local one (specially in California  coats are much higher than in other states).

Magnesium Anti-corrosion Protection

Being very active, Porsche coated inside of the Intake Manifold.  This coating, and any material fill used to eliminate or minimize casting imperfections, will be removed.  Question is how to address the issue of future corrosion.   It appears that it depend on the finish type:

• Powder Coating - there is a concern that hard powder coating chips may enter engine (in some cases, such chips were found in the engine oil) and it is often not recommended to powder coat inside.
• Paint - this concern seems to apply to a paint, maybe due to differences in chip hardness between coatings and paint.
  
• TAG Company  has one of the best corrosion protection processes for magnesium and it's alloys (check Boeing Technical Paper link on this process on their site - it finds it to be superior.   TAG advised that manifold and covers could be tagnited for $150 but they must be shipped to North Dakota!   Parts may be baked after tagniting to out gas them.  Tagnited surface has superior paint adhesion capability as well.  Here is my correspondence with TAG on this.
  

Since I did not have time to ship parts to North Dakota, I have selected the paint option that was done by Exotic Motorworks  for $300 (intake manifold, valve covers, and "flappy" valve bearing replacement.   They did paint manifold inside to reduce exposure to magnesium corrosion.

Finished Parts

• Fuel rail covers painted black with VHT High  Temp engine enamel  (after 2000 miles paint holds up very well);
• Control cable  bracket and levers painted with VHT Hit Temp Engine Enamel - Gray  (easy to disassemble, cover shaft sides of each lever before spraying);
• Main parts painted in Black Chrome.
  

Manifold Close-ups

In the car

Air ducts are sprayed with thin layer of VHT SP-124 GLOSS BLACK high temp engine enamel.

HOODLINER UPGRADE

Hoodliner replaced with Dynamat Hoodliner (best source here), applied over the Dynamat Extreme (best source e-Bay by far: 36 SQ Ft under $100)

I have used 3M General Purpose Adhesive Cleaner 08984 to remove old glue.  I had to cut Dynamat Extreme into smaller piece since attaching one large piece is almost impossible.  Required corrections require undoing attached piece.  Dynamat Extreme adhesive force to the clean hood surface is so high that the hood sheet metal significantly deforms when pulling incorrectly placed Dynamat back.  Damage to the hood is possible.  Smaller pieces can be placed with ease to cover entire area.

Dynamat Extreme

Daynamat Hoodliner over Dynamat Extreme

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