While there is some difference in fuel and age I would suspect the Irvine is marginally better (perhaps it's BB).

10% Nitro makes my 40LA sing. Sure it's no powerhouse but it actually outperforms a 46LA.

Taking RPM measurements and comparing in flight similar aircraft:

40LA with 10x6 prop on 10% = 11500RPM
46LA with 11x6 prop on 5% = 9500RPM

If I assume the increase in capacity is offset by the increase in prop size (46) then I can't understand how 5% extra nitro can account for another 2000RPM. I don't see that on other engines when changing nitro content.

In the air, my 40LA performed marginally better in top speed but the 46 definitely had more initial power.