Yep i can confirm that! those secondaries suck alot of juice when your giving it a bootfull! and its hard not to give it a bootfull after you install a webber, soooooo much better than the hitachi set-up.
when i took mine into a mate to tune, he said that typically it's the next jet size up or down depending on the carby and what it was tuned for, mine wwas off a 2lt escort so he down sized the jet from memory.