Question modified stock kernel

There are many custom kernels for KK, but not one for stock ROM JB 4.1.2...
Is it too difficult to modify stock kernel (adding some governors and schedulers)?
Or what´s the reason for that?
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slimKAT 4.4.4-------------3.0.101-blackhawk+ -------------XXANF2-------------TWRP 2.8.0.1
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