Garcons debilles is pure hip-hop, nothing to do with metal or rock. 'Pedofiele paster' was quite popular when I was a kid (they came around about the same time as ABN, Thof van commerce,...the first wave of Flemish rap linked closely with the success of Osdorp Posse in The Netherlands).
Frank drank is often seen in Aalst, JC still plays in local bands, Hans used to sit in the Nega from time to time, same for Koen. Danny from the Nega played in the Pitbull boys for a while etc. Most of those guys didn't get out of Aalst either
By the way, don't know if you saw, there's a book on the local music history released recently. Some small features on Smurfpunx, Kiet, Gele limonada,...and rather big feature on Onion dolls/Crossfire and Irish coffee.