So considering this thread is for GC8...
PowerFC - $1000-$1500
Vipec - $2000-2500
ECUtek - $2000 (assuming similar cost to a stage 3 for GD)
Autronics - $?
Motec - $? (PNP board for a 99/00 is $2800ish + features + tuning time)
All are far superior to the stock
ecu.
All information talking about GD/GR
ECU's in here is just a waste of time as it is a completely different kettle of fish.
If I had a 99, it would have a motec pnp in there right now.