I bought a '09 yz450f, that had a JD kit in it. It was jetted for a different altitude, so I need to lean it out a bit. The Jet on the left is a 170 from the JD kit, and the 2 others are a 168 and a 165 from the local dealer. Notice the "collar" inside is quite a bit deeper on the jets from the dealer than the JD one. Also, the JD one has a little sort of half star design and the others say "AB" on them. Can anyone help me out with the difference between the two? And, will going from a 170 "shallow collar" to a 165 with the deeper one have the same effect as two that are the same? Any help would be greatly appreciated!