Okay - I'm first to take the piss out of people saying they have big power gains from this stuff, but I just put in a bottle of STP octane booster and I swear there is a marked difference in power. It is most noticable at around 4000-6000rpm.
This is the first time I've used Octane booster since I advanced the ignition by 5 degrees.
The increase in power could point to the fact that I may have over done the ignition advance a bit, as a power increase should be matched with the correct octane level.
When speaking to Arno at Billing, he was saying that there is a point where you advance the ignition and gain more power, but put too much on and it can drop again - too much more and you get detonation. Obviously, octane booster will make the peak power available at a high ignition advance...... He was speaking with regard to the C20LET, but I assume the same could be true for the C20XE - is it?
I'll have to look my own figures up when I'm home, but what are you MBE guys running with regard to you full throttle ignition advance? Why not post the whole row from your map here (may be worth stating your estimated compression too).
Anyway, I'm happy and yep - I'll be using some at SantaPod this weekend.