there's only 1 model of z32 maf
and they're not just "mainly" for big boost - they're essential for it (the stock afm acts a bit like a wrc restrictor)
the factory afm is so small that even a stock standard car would be able to notice the difference (its the same basic principle as exhaust size for turbos, minus the heat dissipation issues - the more air you can flow the better the response)