Does any one know who makes a 1911 38 super mag extension ??

Do you mean to add extra rounds or just add length? To add length most 1911 45 mag pads will work on Super mags. The largest capacity .38 Super I've seen is 10rds. I've never seen a mag extension that added rounds to a 1911 mag.

To add rounds I've seen chip 170mm 15 round power mags

Yes several companies make the 10rd .45 170mm mags, but I've never seen them for .38 Super.