Jetting 2017 KTM 250 XC-W for 2500+ ft?

I have a 2017 250 XC-W. In texas hill country we are at about 500 ft. With the stock Mikuni carb, a 455 jet works fine. 450 is also OK.

I went to West Texas this weekend where the altitude is 2500+ ft. I put in a 445 jet. The power delivery seemed extremely lazy with a very late, but noticable hit. Is it possible I am still running rich? Power delivery was still smooth, but it had none of the "zing" that I am used to in 1st and 2nd gear. I'm only 155 lbs so normally it feels like a rocket on short hill climbs. This really made the bike a bear to ride. 

I have the yellow spring in the bike

Forgot to mention, I am running Amsoil Saber @ 75:1

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