@hcch

Assuming that you ask for for existence of some upgrade for nüvi 255w within the thread topic.

The JNX patcher and related patched firmwares is only for Garmin units that uses JNX files.
Code:
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Also look at post [Only registered and activated users can see links. ]. It's actually the post before your own and you should have read that and got the answer before posting your question.