I have the same question so I'll be watching this...
I've had a quote from "Celtic Tuning". A 30% increase in both HP and torque seems too good to be true with no uprated components for £295 all in (and they come to you!).
170BHP --> 227BHP
359Nm --> 421Nm
https://www.celtictuning.co.uk/component/ctvc/audi/a4-b8-2008-2014/diesel/2-0-tdi-cr-170-bhp-2008-2014-ECU-remap-chiptuning/stage-1?year=2012#t3-content