as for the front, i'm not sure if one has been made yet. although i'm sure someone somewhere has made them for the front, it's down to the awkward shape of the scuttle pannel and petruding over the strut tops
Whiteline make a rear anti roll bar for the clio mk2. It fits the 133 so should go on a GT as well.
Alternatively, maybe look into replacing the rear beam with one from a 133 :? Ive previously posted the measurement for the torsion bar diameter.
Front end, does the gt subframe have brackets for an ARB to be bolted onto it? Your lower arms are simillar to clio presses steeel ones, so a 172 arb may give an option