Harley Davidson Evolution TP smart oil pump UPGRADE 73-91 big twins Total Performance Shovelhead and Evolution modelsHarley Davidson TP smart oil pump 73 91 big twins. Condition BNIB Polished billet Total Performance smart oil pump pumps the oil through the filter first before putting in into the engine like Japanese bikes. Unless you know Harley filter oil AFTER the engine !! way higher pressures than standard especially at tickover where stock pumps do not do much at all Allow you to use twincam oil filters for better filtration on big twin evolution engines. This