My car wouldn't run right with with chrome box? Believe me I tried. It ran great with MSD that is when it ran. I should add this a built motor, 410 roller cam Eddy ported heads. The box I'm using isn't an actual MSD it's Summits version and I think it's working fine. I think it's something else that's the problem.
Note that I said an "older chrome box". Chrome boxes work fine with much more radical combos than this. The new Chinesium knock offs have their own set of issues. Or, as stated above, FBO.