[Quicksilver]

People have maligned the barn door AFM for years but it isn't a source of inefficiency on the 3.2l engine. Talk to the people who have worked on hundreds of these cars and they agree. (Bruce Anderson coined the term, "It is a cash flow device. Jerry Woods reported a 5hp loss with the AutoAuthority MAF. I recently spent a week with the owner of a major LA shop and when MAFs came up he volunteered that no one had one that was better than a barndoor.)

There have been a number of MAF conversion products and no one has had one that performs better than the original. The closest you can come to an improvement is when it comes with a chip to retune the engine but retuning would make comparable improvements in an AFM equipped engine (by narrowing the safety margins that Porsche built into their chip).

There are some conditions where I would expect an MAF to out perform the AFM. When you are dealing with major altitude changes such as climbing Pikes Peak an MAF should perform better. When the basic parameters of the engine have changed such as displacement, RPM range, compressed induction, etc and you would have to completely retune the engine anyway and that would put the MAF on equal footing and if you had a truly increased air flow requirement the MAF could be a clear winner.

Just don't go spending major money on an MAF expecting to find a magical source of horsepower that Porsche missed out on. They didn't screw up the intake.
(If you want "more" look at the exhaust. There is about 20 HP to be found there by ditching the stock exhaust.)