This is my first time adjusting valves on a thumper so bare with me. I have a 00 yz426 that I bought from the original owner (who barly rode it)and I wanted to make sure valve clearance was in speck. All three intakes were at .005 and both exhaust were at .007. The intakes had #179 pads on outside valves and 175 in the center. My shop manual on a '01 426 says (according to chart) to replace the 179's with 175's. What I dont understand is; From what I hear the valves tend to get tighter and if the speck tolerances call for between .010 and .015 by installing what the chart says I will theareticly be at .09. If I went to 170's I will at .014. And on the center one should i go with the (called for 170, or 165. to put me at .015. I guess the main question is is it better to be on the high end or low end of specs? Thanks in advance for advise!