Problem sorted. Ecu needed battery to be disconnected for a while. Damn thing remembers knock retards for a long,long time. Now no retard on the toluene mix.
I would not suggest experimenting with fuels unless you're OK with serious and expensive engine damage. A professionally tuned R32 engine doesn't see much power improvement over OEM because AFR and ignition timing are not what holds the engine back, airflow is. Think cams, exhaust, etc. The OE R32 especially the MKV is a well developed engine. To achieve significantly higher power requires turning the engine into a high performance oriented engine or the use of forced induction - which is generally the best choice when done properly because you get large power gains across the entire operating range.