There is an article on AvWeb that might be helpful. There is a section
of the article titled Flying High that starts about 3/4 of the way down
the article that would most directly address the topic.

http://www.avweb.com/articles/magcheck/

Bruce Bohannon had to switch to pressurized mags for his record attempts
in the Tiger. I don't have first hand details though.

Don Parsons