Or remove the immobiliser from the ecu?

The immob is in the clocks is it not? Which means i wouldn't have to change anything in that area if I didn't change them no? The s3 dash wouldnt line up with the door cards and I'm not a big fan of the s3 dash anyway!

I'm really surprised this hasn't been done before!

 

Exactly, you won't be able to match the Octavia clocks to the S3 ECU unless you de immobilise it.

 

And its been done before, to a greater extent. Plenty of high power Octavia 4x4s historically.

I thought the S3 instrument cluster might just slot in to Octy dash??