Manhattan GMAT Quant Prep Book - Advice on which one?

I did say my weakness is Quant. If you're referring to what my weakness is within Quant, then Data Sufficiency. Even though I know my weaknesses, I'm not sure which books are best for this. The titles don't really tell me that much about what's inside. "Math Solutions Guide" & "Math Study Guide". It appears that Math Study Guide would be more general than Math Solutions Guide. I already have the OG11 and Kaplan800. So many people seem to rave about Manhattan, I think it's worth checking out. I'm also thinking of pushing back the date i retake the GMAT. I was going to take it again June 4th, but I think putting it off another 2 weeks would be better.