I have 433 and 436's and no thump at turn-on. I do have a thump when the 433 fires up using a jack to start from the processor.
Note: I had a thump using a jack at startup with one of the 436's as I didn't have the rj45 plug but after using the rj12 to rj45 plug between amps for link the thump stopped.
Note: I had a thump using a jack at startup with one of the 436's as I didn't have the rj45 plug but after using the rj12 to rj45 plug between amps for link the thump stopped.