Fang (fan) Duct R2 for Tevo Tarantula Dual Extruder Stock

Hi All,

Further to some tests and review over the web, it seems that cooling can be improved. Also i found out that some backflow can happen due to restriction at the outlet of the Fang.
So i designed a new one, with bigger outlet which should reduce the pressure against the fan 40x40x10 are not able to go against. I also take the opportunity to improve the "printablity" (not sure this word exist ^^).
So it can be printed with 2 walls thickness and 0% infill (for who wants to try clear fil