Yes, any bypass filter needs a restrictor. It's built into the standpipe of the original canister filter like a Fram or AC. If I'm using a spin-on adapter for that vastly inferior type of filter for some reason, I adapt a Holley carburetor main jet to one of the fittings upstream of the filter. If a customer insists on the spin-on over my objections, that's how it needs to be done. I absolutely will not run that type of filter on an engine I build for myself, unless I'm using a much finer-mesh filter media than is usually used for engine oil. Some spin on ilters for hydraulic fluid have a 1-micron rating instead of the 10-20 micron size that's generally used on a full flow filter. A Diesel fuel filter for an 18 wheeler engine also works well in a bypass configuration for engine oil on a stovebolt.
Jerry
