Pinking under boost with just 9 degrees of advance

[bertelli_1]

I have been running my mk2 Golf on 99RON fuel since the engine conversion but now fuel costs a small fortune I have switched to 95RON. Ignition advance is 9 deg around 3000 rpm at 180kpa, above and below this area I can run a lot more ignition - its like I have a 'hole' in my map in this area. The car runs fine with this amount of advance (although I'm going to have to take more ignition out to cope with 95). I have been considering swapping to a colder spark plug but even the high output versions of my engine (VAG 1.8T) use the same heat range. I have verified my base timing.
So do I just run with such a small amount of ignition, try colder plugs or something else entirely?

[bertelli_1]

Comp ratio is 9.5:1, it is intercooled, my manifold temperature is generally around 10-25 deg c above ambient (not excessive) although I am working on a cold air feed.

[bertelli_1]

I am confident my base timing is fine - and I'm assuming the ecu is adjusting the spark timing correctly! AFR is around 11.8 - 12.1 in that area of the map.

[bertelli_1]

E - I'm running BKUR6ET - the standard plug for the engine. The high output versions (225bhp) use a PFR6Q. I haven't tried going colder but may give it a go (PFR7Q are available). Not sure what tips they are, ngk list as a 19mm reach.