These are to replace the factory Prechamber inserts, no welding, no grinding. Simply hammer the old out and tap these in. The reinforced design adds mass and strength, the Inconel 718 is almost indestructible under high heat and stress. These have been extensively tested in 500+ hp engines. Egt temps recorded over 1600F for 30k+ miles. If a stock inserts breaks, it could cause lots of damage to the engine, possibly ruining the head, piston, and block. Cheap insurance to keep your balls intact.