Replacing your stock oil pump with Melling's high volume pump is recommended during engine upgrades.  Melling builds these pumps with a larger inlet hole and hardened steel gears that are up to 25% longer which provides additional oil flow for wider bearing clearances. The drive and idler shafts have been extended into the cover to provide additional support and eliminate any shaft deflection. The pressure relief spring plug is threaded for easy replacement and a heavy duty drive shaft with a steel sleeve and extra spring are included.  All pumps are 100% pressure tested and hand-turned before shipping. This attention to detail ensures you that a quality oil pump is being installed into your engine.  Oil pump screens, driveshafts, and pickups are sold separately.