I only installed grill prefilter kit and seemed to work in the deep stuff just fine but on new years day we brought a few newbies up (1 12 yr old with a smile ear to ear riding a 97 440 ) and i had to take out the filter half way up to riding area as he was a little timmid and still only 20 deg out it just wouldn't cool it enough at 17 to 22 mph as this sled is use to rippin up the roads to get to riding areas (all of our sleds had this issue yesterday except aircooled 440) however on his ride back 25 to 50 mph .