F-22 RAM Coatings/Limits on speed?

A U.S Air Force F-22 Raptor with the 1st Fighter Wing, Joint Base Langley-Eustis, Va., moves in to be refueled by a KC-10 Extender with the 78th Air Refueling Squadron, 514th Air Mobility Wing, over the Atlantic Ocean, Feb. 14, 2018.

A pretty well researched video on the role of modern RAM materials in reducing RCS.
It looks like RAM is playing a bigger role than it did before on RCS reductions

Good video. The mitigation of creeping wave return effect may have been inadvertently referenced in this unsecure exchange:

Radar Technician: I'm having trouble with the radar, sir.
Dark Helmet: What's wrong with it?
Radar Technician: I've lost the bleeps, I've lost the sweeps, and I've lost the creeps.

preceded by:

Dark Helmet: [looking at Mr. Coffee] What's the matter with this thing, what's all that churnning and bubbling, you call that radar screen?
Colonel Sandurz: No, sir. We call it,
[slaps the machine]
Colonel Sandurz: Mr Coffee. Care for some?
[prepairs a cup for Helmet]
Dark Helmet: Yes. I always have my coffee when I watch radar, you know that.

Radar Technician: The radars been jammed sir.
Dark Helmet: Raspberry