I've extended my 2004 xcsp to a 144 incher. The tracks usa tunnel extension has straight across mounting holes where the original tunnel had the outer mount holes higher than the center three. I've read about some overheating issues from too short of a flap so I'd like something longer than original. I've checked other polaris flaps in the catalog and it seems there all about the same length. I've measured out some flaps on my other sleds and a IQ rear flap seems to be the longest. Any ideas ??? Thanks in advance.