ECU flash tune VS powercommander /dyno tune diference

[draughtrider]

So to put a simple spin on this, I could buy an X-TRE, I could buy a PCx but I can leave everything pretty much stock and achieve the same things with room for much more 'down the track' if I so desire, If I get the Woolich. Seems like a no-brainer. Can add the logger and o2 stuff later if needed.

Question re reflashing, can this fix speedo also? (does speedo need fixing? I try not to look at it ...)

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... and the supplementary question - Woolich has 15 ECU's listed for Gen2. If I were to acquire a second ECU 'for fun' so I could literally leave the first untouched in any way, would I have to match exactly or would any do (plus or minus minor fixes/etc) ...