Front Sprocket Size

I've been running a 15 tooth front sprocket on an '08 GSXR. On track I never use 1st gear and don't use 2nd very often (probably should use it more often). Reading as much as I can about driveline efficiency, it seems like I might see a bit more real-world, rear-wheel power if I moved to an 18 tooth front sprocket and utilized more 1st and 2nd gear on track. The issue is NOT overall gearing -- it's driveline efficiency.



Does anyone have any experience with this issue? Opinion? Or even (gasp) data?



Thanks.