An assembly (200, 300, 400, 500, 900) comprising: a housing (210, 310, 410, 510, 910) that comprises a bore, a wastegate opening (224, 424, 524, 924) and a wastegate seat defined by a surface surrounding the wastegate opening (224, 424, 524, 924); a mono-block arm and plug that comprises: a material of construction; an arm portion that comprises a free end configured for receipt by the bore of the housing (210, 310, 410, 510, 910), a plug end and a shaft portion therebetween having a rotational axis z a; and a plug portion (650, 850, 950, 955) extending from the arm portion wherein the plug portion (650, 850, 950, 955) comprises an outer edge at an outer radius r p, a face (660, 960) and a deformable ridge (670, 870, 970, 975) that comprises a cross-section, the deformable ridge (670, 870, 970, 975) disposed at a radius r r defined from a point on the face (660, 960) and the cross-section having a radial thickness Δr r dimension and a height Δz r dimension extending outwardly from the face (660, 960) wherein a surface of the plug portion extends a radial distance Δr s from the deformable ridge (670, 870, 970, 975) to the outer edge of the plug portion (650, 850, 950, 955); wherein the cross-section dimensions Δr r and Δz r of the deformable ridge (670, 870, 970, 975) of the plug portion (650, 850, 950, 955) are configured to change via deformation of the material of construction responsive to application of force that rotates the shaft portion in the bore of the housing (210, 310, 410, 510, 910) to position the machined ridge (670, 870, 970, 975) against the wastegate seat for closing the wastegate opening (224, 424, 524, 924), wherein Δr r / Δz r is in the range 0.2 to 1. a housing (210, 310, 410, 510, 910) that comprises a bore, a wastegate opening (224, 424, 524, 924) and a wastegate seat defined by a surface surrounding the wastegate opening (224, 424, 524, 924); a mono-block arm and plug that comprises: a material of construction; an arm portion that comprises a free end configured for receipt by the bore of the housing (210, 310, 410, 510, 910), a plug end and a shaft portion therebetween having a rotational axis z a; and a plug portion (650, 850, 950, 955) extending from the arm portion wherein the plug portion (650, 850, 950, 955) comprises an outer edge at an outer radius r p, a face (660, 960) and a deformable ridge (670, 870, 970, 975) that comprises a cross-section, the deformable ridge (670, 870, 970, 975) disposed at a radius r r defined from a point on the face (660, 960) and the cross-section having a radial thickness Δr r dimension and a height Δz r dimension extending outwardly from the face (660, 960) wherein a surface of the plug portion extends a radial distance Δr s from the deformable ridge (670, 870, 970, 975) to the outer edge of the plug portion (650, 850, 950, 955); a material of construction; an arm portion that comprises a free end configured for receipt by the bore of the housing (210, 310, 410, 510, 910), a plug end and a shaft portion therebetween having a rotational axis z a; and a plug portion (650, 850, 950, 955) extending from the arm portion wherein the plug portion (650, 850, 950, 955) comprises an outer edge at an outer radius r p, a face (660, 960) and a deformable ridge (670, 870, 970, 975) that comprises a cross-section, the deformable ridge (670, 870, 970, 975) disposed at a radius r r defined from a point on the face (660, 960) and the cross-section having a radial thickness Δr r dimension and a height Δz r dimension extending outwardly from the face (660, 960) wherein a surface of the plug portion extends a radial distance Δr s from the deformable ridge (670, 870, 970, 975) to the outer edge of the plug portion (650, 850, 950, 955); wherein the cross-section dimensions Δr r and Δz r of the deformable ridge (670, 870, 970, 975) of the plug portion (650, 850, 950, 955) are configured to change via deformation of the material of construction responsive to application of force that rotates the shaft portion in the bore of the housing (210, 310, 410, 510, 910) to position the machined ridge (670, 870, 970, 975) against the wastegate seat for closing the wastegate opening (224, 424, 524, 924), wherein Δr r / Δz r is in the range 0.2 to 1.