Colorado 07 YZ450

Can anyone provide some recommendations on jetting. I have the stock jetting now but when I let off the the gas the bike backfires.

Here is what I am thinking

Main Jet: 160 no change

Pilot Jet: 45 (go to 48)

Starter Jet: 72 no change

Leak Jet (if any): 55 no change

Fuel screw/Setting: 1.25-1.75 turns out (adjust according)

Needle/Position: NFLR-4 (move the needle on 1 notch leaner)

Altitude is 5-9K

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