Yamaha DTXpress/DTXplorer/DTXtreme

I'm really new to the dtxpressII and all e-drums in general, but I 
was wondering if anyone has a sysex bank containg, or a way of 
creating, one of those super low bass drop sounds for the dtxpress.  
I've been trying to make my own from the sounds on the kit and have 
been running into problems.  Then I tried getting the midi sound 
itself and making my own sysex file to send to the unit, but I have 
no clue what to do with all of that stuff.  Any of you gurus have 
any advice on that? thanks