The Pull-Slap (Part 8 - Defined)
A slap starts with the tongue off the harmonica... so it is essentially not articulated. What do I mean by "articulated?" Play 4 draw many times using Ha Ha Ha Ha... this is your diaphragm pushing little bursts of air through the harp. Now play it with Ka Ka Ka Ka... this is articulated. Each "K" stops the air and then allows it to burst back through the harp... it's "sharp."
So, a slap is not articulate (airway is open when you start to breathe). A pull-slap is articulate (airway starts closed as you start to breathe and then opens for the pull). Start with your tongue on the harmonica (everything is closed, just like it was for "K" in our example). Pull off and immediately slap.
The time it takes to do a slap and a pull-slap are the same, the only difference is that your pull-slap start with the tongue on the harmonica. Do a slap, then start with your tongue on the harmonica (covering all holes) and perform a pull-slap. If you do slap, pull-slap, slap, pull slap... the rhythm should be the same for each one... each should sound very similar, the pull-slap just having more "pop" or "snap."
Experiment with this...