ORIGINAL: w8ye
I know that the #4 has no curve at all. It switches from no advance to full advance around 2200 rpm.
More of a "step" than a "curve" as I understand it. The DLE 30 uses a #3 module, has a similar single step. Those are the only ones that have that that I've read about.
Either can/will cause a little trouble when first tuning, but if the throttle linkage is set up properly, it's not bad to deal with at all. Both engines run best/most reliably kind of fat on the idle. NOT a big deal.....