Has anyone tried a 40 tooth rear sprocket?

[gahmp]

Hello all,
I've had a GZ250 for almost a year now. I love it. It does everything I need it to do. I would however like to take it down the highway at 65-70 MPH without feeling like I'm killing my sweet machine. I have read many posts in which the front sprocket was changed from the stock 15 tooth to a 16 tooth. This would take the gear ratio from 2.733 to 2.5625. I have read a lot of complaints that after the switch the top end speed goes south. If I were to change the rear sprocket from the stock 41 tooth to a 40 tooth it would give me a gear ratio of 2.666. That would fall pretty much in the middle of the differential between a 15 and 16 tooth front sprocket. I'm thinking that the one tooth off the rear sprocket will be enough to keep the bike in it's power band therefore allowing maybe a little extra power at highway speeds while simultaneously reducing the rpm's its kicking out and all the while improving the MPG's. (I know I'm a dreamer) If anyone has tried this mod please share your results.