As far as tires go, talk to the locals and go with their recommended tire/sauce combo.
When I raced at SDRC I ran Raw Speed Slicks Gumball with PB Blaster for sauce and I was dialed ;)
I used to race with a center slipper on my 13.5 wheeler for years, I knew better that I needed to install a center diff when I traveled to race at SDRC in SoCal which is indoor clay. I actually started with 10K but found 60K to be the sweet spot.
Out of laziness I left the 60K in it when I...