GT1R Oil Filter Adapter
The OE Nissan and equivalent size oil filters are designed for light weight oil, OE spec is 0w40. As the viscosity increases, which is common in high-performance rebuilds (GT1R engines are spec’d for 20w50 oil), the factory filter begins to become a restriction to the thicker oil.
Most filters have a bypass that opens around 10psi differential oil pressure. What this means is when the pressure on the inlet side of the filter becomes 10psi higher than the pressure on the outlet side of the filter, the bypass opens and you get unfiltered oil passing into the engine. This is bad for obvious reasons.
Designed for racing oils
The WIX Racing filters are designed for thicker racing oils and higher oil flow rates (which comes with increased RPM). While their filtration spec isn’t quite as good, ~60 micron vs ~ 35 micron, all of your oil is being filtered. 60 micron is better than no filtration! The Racing filter flows 28gpm, where the XP version flows 9-11gpm.