Freaky. I remember putting gas a couple of old v8's I owned. The peak torque area moved UP about 1000 revs.
Also I don't think unleaded takes you 30% further, LPG is something like 8-10% less efficient without making other changes to the engine, eg ecu and cams.
I thought it actally burned hotter than petrol which was why one of the age old drawbacks of it was burnt out valves, particularly on engines designed to run on leaded fuel without hardened valve seats.