Sorry mate they are not H4's as far as i know! Mk4 Golf has H4's.
Mk3 GTI has twin head lights so you have 2 bulbs, one for main beam, one for dipped, in both lights. 4 bulbs in total. They are all H1 bulbs. Side lights are Wedge bulbs and fogs are H3's.
I had problems finding out when i changed my bulbs but my car is a 98/R 8 valve GTI. Non GTI models and older GTI's may be different!
Hope this helps let me know how you get on.