6 years and 180K miles, my 400 just isnt cutting it any more. Did a mudrace this last weekend and got beat by people that used to not be a problem. Also, 2 passes = 2 quarts of oil and it wouldnt pull 2nd in the mud. I've got the engine in the garage ready to go in. I've got to get it done by Saturday as there is another race. I cant wait!