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I personally believe the 987 OEM filter has one big advantage in that the larger filter area over the 986 (14.5 sqft vs 6.1sqft) not only gives a lower pressure drop but also a significant longevity to the element. In other words the element maintains the benefits of the lower pressure drop for a sustained period as it takes longer for the element to be come contaminated and restrictive. This type of cone filter is normally used in race applications where the filter is either replaced or cleaned and re oiled after a relatively short period (ie one race).
Providing the cone filter can be located somewhere accessible and the owner is happy to clean the element frequently , the next issue is contamination of the MAF from oil carry over. An air box and indirect route to the MAF should reduce some of the risk of oil contamination as the oil will drop out of suspension in the air at lower velocities where the diameter of the air tract increases and velocities reduce. A silicone hose direct from the inlet cone filter doesn't allow the velocities to drop so the MAF is more at risk from contamination. I believe there were revisions on the MAF design on both the 986 and between 986 and 987 whereby additional screens were placed in front of the element on the 987 to protect it.
Of the cone element installs I've seen , they all seem to rely on removing the baffle plate in front of the air box to give better flow. Whilst this does indeed work it also increases the risk of water droplets getting onto the MAF or in extreme cases making
the filter wet and losing capacity.
I think that to make a satisfactory street version of an intake system all these elements need to be considered. If the aim is purely to make a track orientated modification then a cone filter and silicone tube will give the best results for minimum outlay.
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