Saying thanks!
Picked up 2003 A4 Avant in good working condition. Was thinking of spending approx $500 CAD on a stage 1 tune...
Eventually found this forum, joined, learned. Had 'blue cable' already. Took the advice of using a car charger to keep the voltage up.
Backed up my BIN. Flashed stock bin. Would not start - flash back to my BIN. Car OK again.
Learned to edit that single HEX value in stock file and then re-checksum it. Flashed stock BIN again, car works fine.
Stage 1 V7 BIN did not have that HEX value, so flashed it. Car works fine. Pulls noticeably harder and runs just like stock. Awesome!
BIG THANKS
It's like a Christmas present to myself!