456 gear with 29.5 slicks!

there 29.5/9/15s fixing to put in the gear and put the slicks on im just trying to figure out how bad its gonna kill my gear
I am running this same tire / gear combo in my Demon with 380 hp 360. I shift at 5800 and run out the back at 6100. ET 11.81, MPH 113.0
Chuck.