I have never purchased any IMI ammo.
Winchester Q3131A is supposed to be THE ammo choice for 5.56mm. I have shot enough to try it out, but I did not specifically test it for flash. It is made by IMI, and supposedly is exactly the same as the ammo you asked about.
I have been shooting PMP (south African) a lot. In the 20rd. Gazzelle box. It has fairly low flash. I tried the South African battle packs (Denel), huge flash. Did not like it.
A friend and I were out shooting bowling pins one day with our AR-15s. I was using PMP, he had some brand of hollow point. I was shooting through the pins, hitting them repeatedly without knocking them over. He was knocking them down with each shot. I'm thinking about a few hundred rounds of some type of expanding ammo now, although I haven't picked a round yet. Not frangible ammo. I'll still keep a wad of Q3131A on hand.