Feuling recommends Race Series lifters for engines running higher than 185 Lbs. valve spring seat pressure. FEULING recommends the use of a high volume oil pump which will result in quieter, better performing lifters. Race Series lifters are compatible with either FEULING HP+ or Race Series oil pumps and are designed for use with both street and strip engines. Spin-Tron dyno developed and track proven, Made in the USA.