Trans Am Race Engineering Superlite 17x8 - now available with a useful backspace?

72bluNblu, quick easy question...If I have a 17x8 wheel with 5.75" backspace, and I add a 3/8" spacer am I increasing or decreasing the backspace? I forget how it works. That would make a 17x8 wheel with an effective BS of 6.125 or 5.375 ?