I have used 100ron petrol in my my00 for a few years now and not really had a problem with it.

A few months ago I changed my flywheel and fitted a Walbro 285 fuel pump now I have a boost problem on full throttle when using 100 ron petrol.

it boosts up to 1.2 bar then immediatelly drops to 0.4 bar then ups to 1.2 then drops to 0.4 and it keeps doing this until I need to slow down.

I had to use 98 ron on sunday and the problem stopped and I could accelerate hard normally.

I have a new fuel regulator to fit but and at first I thought this could be a fuel pressure problem but after changing from 100 to 98 ron petrol and the problem stopping I decided it was not the case.

I have a standard off the shelf Tek 2 ECU from the UK if this helps any.

Cheers

Steve