Hmmm...Its true that these sort of super tight engines dont fully wake up until about a gallon but I dont think you would necessarily do a run in for 6L(1.5Ga) before hammering it, despite what the instructions say. They are built like the more famous Italian engines like novarossi which have the famously tight pinch. After about 1L your engine will be be basically run in but they dont consider it totally run in as the engine wont fully "open up" until about a gallon of fuel as been run. That doesn;t mean you draw the run in process right out into 6L just because the pinch is super tight. You can actually damage your engine if your prolong the runin especially if its at a rich and cold settings. These are a no tighter than a novarossi or RB and I can tell you are letting your engine go to waste if you are not running it to near full power during the that first 4-6L. I would find it pretty weird if these engines are the ONLY ones that need feathering for the first gallon. They would be the only engine if that was the case.
I have a Sirio Kanai & a RB WS7, both known for super tight tolerances. Both those engines take about 1L to runin but they practically needed to be heated up and the plug loosened for the entire 1st gallon. You certianly dont go feathering it about thats sure!! These are race engines first and foremost and they are intended to be raced ASAP.
Now I know that's going to kick up some debate but its not intended to. Its an opinion but its something that most pro racers and engine modders have told me and they all say the same thing.
I have read many reports about people snapping the conrods in these engines during that first gallon and I can almost guarantee that its because they prolonged the runin far too long and ran their engines too rich which would result in all these conrods breaking. Anyway just something to think about?
I see, interested in the method of break in, you didnt just idle trough 1.5 gal did you?
And G*man, NEVER EVER idle through 1.5 gallons!!!! Infact you really shouldn't ever idle for a runin. You need to get the car onto the road ASAP so you can put load on the enine and bulid up the engine temp. Getting the engine upto at least 200F as soon as you can. I you use an idle runin all that does is runin the engine at low revs and you wont get the right tolerances with the piston & sleeve.