just wondering whats the best 450 shocks to put on my 04 kfx 400? and will any modifications need to be done?

I have an 06 KFX 400 all stock. When warming up it idles high with choke on about 8 inches of the pipe glows cherry red. When i took choke off and it idled down it went away but when i started to rev it up it would start to glow again. Is this normal or do i need to adjust something. Thanks