Does anyone make a smaller rear sprocket then 37? Id like to gear up more but with the case saver i have i cant bring the counter shaft up more.. its quicker now then itwas with the42 rear, id like to continue gearing up to see how much more acceleration can be had along with top end numbers

Put a case saver that is made for a 15 tooth.  Increasing the tooth count on the countershaft reduces the parasitic losses in the chain and decreases the tensile load on the chain.  A 15 tooth sprocket will also make the chain last longer.

If you found that a 3.00 final drive ratio was the optimum gear ratio, a 45/15 will deliver slightly more power to the rear wheels than a 39/13 sprocket combination.