I never got a close look at an Open class sled this winter. If anyone saw one up close, does the track not extend past the tunnel? I don't think a normal snowflap would be rigid enough to keep from getting caught on the track lugs. The tunnel extension would allow the use of a stock flap. Looking at the attached photo (from the all line brochure) it looks like they spliced some metal or rubber between the snow flap & the tunnel. The flap looks like a OEM part.