Here’s some gearing recommendations from various tracks.  If you’ve got a recommendation add it here.

From Michael Bateman:

I’m currently using 17/34 at Pacific Raceways on a 175.

From Stephen Gillen:

Miller: 175sloper, 17/37 worked very well (tried 18/38 never got into 5th, ran like a 160 around the circuit)

Willow: 175s 17/38, 18/38 worked but with less drive out of corners, great along the back, all the way back to turn 3