MSD 8387

Does it improve the performance? Paint doesnt...rims (maybe for mass reduction) but cast iron or billet? I had a MP 2 piece billet B distributor. Nice piece: had 2 bearings, a shaft and an advance plate. Same as the iron one I replaced it with. It looked nice, but the iron one fit better. I had to clearance something for the billet one to fit. I sold it and didnt feel a difference between the 2.