The generator matrix

 1  0  0  0  1  1  1 (a+1)X  1  1 (a+1)X  1
 0  1  0  0 (a+1)X+1  X aX+1  1  a aX+a  1 (a+1)X
 0  0  1  0 a+1 (a+1)X+1 (a+1)X+a X+a aX X+1  1  0
 0  0  0  1  1 a+1 X+a X+1 aX+a (a+1)X+1 (a+1)X+a aX+1

generates a code of length 12 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 25.

Homogenous weight enumerator: w(x)=1x^0+156x^25+240x^27+1068x^28+816x^29+864x^30+2160x^31+3306x^32+3912x^33+5184x^34+6480x^35+11220x^36+8304x^37+7776x^38+6480x^39+5358x^40+2172x^41+24x^44+15x^48

The gray image is a linear code over GF(4) with n=48, k=8 and d=25.
This code was found by Heurico 1.16 in 1.49 seconds.