Can I get smaller than a 40 tooth sprocket for my warrior?

 

I believe Sidewinder will make you a non-standard size rear. Their charge is $5 extra for the special size.See their website at sidewinderracing.com
I suppose you must have a good reason for wanting a smaller rear rather than a larger counter shaft?

 

I already have the biggest sprocket on the front and Im thinking of reducing tire size.