Yes, if you have already flashed 34xx fw it's ok:
Unpack the file to an empty SD card, turn nuvi off, insert card, turn nuvi on.
remove sd.
If you want to go back to 37xx:
flash 37xx sw ,insert the sd and you'll return to original 37xx logo and features.

Then don't forget to run Webupdater to get the latest firmware, reset and select Mass Storage in Dev Menu.