here are some sites by the pros to prove my post
http://www.bowhuntingmag.com/tactics...d_flight/#cont

The Well-Tuned Bow
The first thing you have to do is make sure your setup is truly tuned. Don't be fooled into thinking that your bow is in tune because you can shoot tight groups with field points. Field points can be very forgiving, and it's possible for an out-of-tune bow to shoot one-inch groups at 20 yards with field points. (This is why mechanical broadheads tend to group better. They're much more like field points.)



Most broadheads, however, aren't going to let you get away with bad tuning, especially if you have a fast bow. This is because the blades on a broadhead can act like wings and steer an arrow all over a target face. Launch an arrow poorly and the blades will catch air and drift off target right from the start.
read the rest of this artical

http://www.parsonsoutdoors.com/broadhead_tuning.html
http://www.muzzy.com/muzzy_help/broadhead_tuning.htm
http://www.basspro.com/webapp/wcs/st...&storeId=10151
http://www.pabucks.com/broadhead_tuning.html
http://bowsite.com/bowsite/features/...ght/index.html

need I post more I will fill a whole page.Look at these sites before you critise my post....