Super unleaded, keep your ears peeled for any signs of pinking and add octane booster if you have to. I can run 38 degrees of timing with no pinking and no additives.
Best invest in a catalyst in line octane booster if your running h/c and standard valve seats, it brings up to 100 octane unlike additives that don't really work.
Got mine the biggest one for 70 squid at show price money well spent that actually works and stops pinking.
