I have stock gearing now with a 53-50 helix which works very well. I would like to go down maybe a tooth on gearing to get a little more on top. What I want to know is will this kill my bottom end, or will I even notice?

do you have any thing else done to the sled ie... reeds, clutch work silencer... droping a gear is good idile but you must go with some different weights if you truely want to benfit from the lower gear...

I take that you meant you wanted to "add" a tooth, and not "drop" a tooth since you wanted more top end speed (dropping a tooth means smaller gear and hence more BOTTOM end, not top). It also depends if you want to add a tooth to the small gear or the big gear. Adding a tooth to the small gear will of course be a bigger difference than the large gear. You will have to check a ski-doo manual to check what combinations will be able to be used with the stock chain (you may have to replace it for a different pitch). I would call Greg Goodwin at Goodwin Performance at 847-872-4001 for that question. He will tell you exactly what you will loose or gain. My guess is is you will pick up 2-3 mph on the top end for each tooth on the small gear, but you will loose 3-5% of acceleration for each tooth added. The large gear would be less dramatic.

stock is 25/43 yes you can put in a 26 tahat's whast we run.