Actually the Bel RX65 isn't that great for Multanovas. On a good day (at full power, pointing forwards) you may get a couple of hundred meters warning, but on other days you'll get about 40m warning.

The Escort X50 (passport 8500) is better at the low powered Ka Multanovas than the RX65 but if you want the best warning, get a detector that has Ka narrow filter like the Bel 966R and 975R 990i or the Valentine One in Euro mode.

I've been testing the Valentine One (Euro mode turned on) and went passed my first Multanova.

It SMASHED the other detectors for range. Easily beat the Escort X50 (which I was happy with getting between 5 and once 29 seconds warning)

I filmed the Valentine One encounter too, so I'll post the video link if anyone is interested.

I've also been testing the Bel STi which is said to have better range than the Bel RX65 but I haven't found a Multanova with it yet. Without a Ka narrow setting tho, it won't be as good as the V1 I'd imagine.