Well, Sarit's experience is just one data point -- his TBD may well have been dismissed because the officer didn't submit his side. Discovery will be useful at the trial, but from my experience and others on this forum has virtually zero effect on the TBD. The reason is that trying to exclude evidence, etc. all requires more motions, hearings, etc. and the TBD process isn't designed to accommodate all that.
FYI, the
SLO County DA handles all prosecutions for traffic infractions.. I'd recommend you get the venue issue settled before you send a discovery request.
All that said, a 22349(a) is one of the hardest VC speeding charges to legitimately defend (the Sarit blog post is about a 22350 which is MUCH easier). Your best bet is for a procedural error. Also take a look at
this site to get an overall idea of the process, but remember that it's actually very difficult to get a dismissal based on failure to provide (or incomplete) discovery.