IIRC about a 1/2 inch on both grip and slide......
but the CS9 has a "finger rest" on it's 7round mag..... which makes it as tall as a 3913 if you can find a flush fit 7 round mag. (yes they do exist) vs the more common 8rd magazine that also extend below the 3913 grip frame. (note the flat base 8rd mag is shorter then the one with the finger rest..... about 1/4 vs 1/2 inch)
I have several 7rd flush fit magazines and carry IWB so I found 0 sum gain in getting a CS9 ...... so I passed when they first came out.
As some around here say YMMV...."Your mileage may vary"