A suction diffuser or arrangement comprising: a main suction diffuser body (12, 412) configured with an inlet to receive an incoming fluid (F i), an interior cavity to receive the incoming fluid (F i) from the inlet, and an outlet to receive the incoming fluid (F i) from the interior cavity and provide an outgoing fluid (F o), and a flow conditioning arrangement configured in relation to the inlet and comprising a flow conditioning portion (14a, 140, 240, 340, 440, 540) having at least one inwardly contoured surface, configured to extend into the interior cavity, diffuse the incoming fluid (F i) passing from the inlet into the interior cavity, and provide a flow conditioning that produces a uniform flow of the outgoing fluid (F o) by directing the incoming fluid (F i) towards the outlet, based at least partly on a contoured design corresponding to the at least one inwardly contoured surface, characterized in that the flow conditioning arrangement comprises a baffle (16, 145, 345, 445) configured in the interior cavity to restrain or regulate the flow of the fluid from the inlet to the outlet, wherein the baffle (16, 145, 345, 445) includes an end portion configured with a shape that substantially corresponds to the shape of the at least one inwardly contoured surface so as to mate or fit together with the same, and wherein the flow conditioning portion (14a, 140, 240, 340, 440, 540) also has at least one slot (14c 1, 14c 2, 14c 3, 14c 4; 148a 148b, 148c, 148d) configured to receive and engage the end portion of the baffle (16, 145, 345, 445), wherein the at least one slot (14c 1, 14c 2, 14c 3, 14c 4; 148a 148b, 148c, 148d) is formed in the at least one inwardly contoured surface. a main suction diffuser body (12, 412) configured with an inlet to receive an incoming fluid (F i), an interior cavity to receive the incoming fluid (F i) from the inlet, and an outlet to receive the incoming fluid (F i) from the interior cavity and provide an outgoing fluid (F o), and a flow conditioning arrangement configured in relation to the inlet and comprising a flow conditioning portion (14a, 140, 240, 340, 440, 540) having at least one inwardly contoured surface, configured to extend into the interior cavity, diffuse the incoming fluid (F i) passing from the inlet into the interior cavity, and provide a flow conditioning that produces a uniform flow of the outgoing fluid (F o) by directing the incoming fluid (F i) towards the outlet, based at least partly on a contoured design corresponding to the at least one inwardly contoured surface, characterized in that the flow conditioning arrangement comprises a baffle (16, 145, 345, 445) configured in the interior cavity to restrain or regulate the flow of the fluid from the inlet to the outlet, wherein the baffle (16, 145, 345, 445) includes an end portion configured with a shape that substantially corresponds to the shape of the at least one inwardly contoured surface so as to mate or fit together with the same, and wherein the flow conditioning portion (14a, 140, 240, 340, 440, 540) also has at least one slot (14c 1, 14c 2, 14c 3, 14c 4; 148a 148b, 148c, 148d) configured to receive and engage the end portion of the baffle (16, 145, 345, 445), wherein the at least one slot (14c 1, 14c 2, 14c 3, 14c 4; 148a 148b, 148c, 148d) is formed in the at least one inwardly contoured surface.