On the NA impreza I had, texaco was safe bet - never had issues with petrol from them. Its weird, but the NA hawks are very very sensitive to good petrol.
With Bug WRX, I had no issues with any petrol I put in it - still avoiding the super cheap petrol stations, but Topaz, Maxol, Applewood and Texaco all work just fine.
To answer OP question: If you dare and ring the petrol companies, all you get is 'our petrol is fullfilling these and these requirements' but wont get any real info. So expect that all petrol here is 92 with Ethanol additives to fill in 95octane requirement.
If you are getting car imported from Japan - first thing to do, get it mapped on Irish petrol, its pricy, but better safe then sorry