This is pretty old but very eye opening concerning broad head performance. It deals with multiple blade vs. two blade and heavy vs. light arrows. It also deals with quartering to shots when properly equipped. Very good read. http://www.tradgang.com/ashby/Broadhead Performance.htm
Everyone needs to read this information. Two main points I took away... heavy arrows and single blade heads solve a host of penetration issues. Another was the discovery that larger heads did not produce better blood trails. Lots of good stuff here... of course this is old information.
