my 2 paisa of words ..
dont know about cold intake .. whats that .. i am feeling lazy to search about cold intake .. and most importantly if it does improve the performance of cg 125///
if u want a bit free flow filter .. then u can install pod type filter in ur cg .. that wont be as restrictive as stock one and u may notice some benefit..
youtube for honda cg 125 carburettor and watch few videos ..