I'm sorry I'm gonna have to ask this dumb Q. I'm sure some people that doesn't know about it does too. How does an aftermarket oil pump help?
"This pump flows 20% more volume, while maintaining the factory USDM STI peak oil pressure. It is great for high RPM use where your original factory oil pump could not keep up with the needed oil output to properly lubricate your engines internal components. Factory Subaru engines sometimes lack the necessary oil flow and lubrication to the cylinder heads, causing excessive wear that is sometimes seen on the camshaft journals. This pump will reduce wear in these areas."
should be the same part number as this from, http://www.flatironstuning.com/p-1543-jdm-subaru-12mm-oil-pump-kit.aspx
Its a legit Subaru part. It comes from the Dual AVCS Legacy in Japan. I just received one just like this in the mail (from Japan) last week. You should see Fuji's post about the 12mm oil pump if you have further questions.