Hi Jim,

I personally don't believe a gascolator is necessary (neither does the factory) because you don't need to filter twice and the header tank with its drain at the lowest point in the system does the same job as a gascolator for water separation/draining.
I know there has been a lot of debate on this topic. I suppose you could use the header tank for separation - assuming you include it in each pre-flight check for water. If not it is useless for that purpose. The outlet is near the bottom and so it would be prudent to check/drain regularly anyway.

I also don't think the factory would be opposed to using a gascolator if a builder wanted to utilize one. As a point of reference - they are required in Canada.

I guess if you've ever gotten water out of a gascolator you'd be in the believer camp - I'm a believer! Of course if you don't have one, it would be hard to tell until potentially to late.

IMHO,
Greg