The springs, ride height, suspension and camber will all be tweaked "to make the car stiffer because you want it more direct" to suit the six-day event, travelling about 700km from Manukau on Monday to Wellington on Saturday.
Gilmour's team will replace the "dogbox" transmission used in rallies - which allows the Subaru to reach only 180kmh - with a six-speed synchro gearbox that elicits a top speed of more than 210kmh.
Not that Hamilton-based Gilmour will test its upper echelons.
All cars have a 200kmh maximum they can not break and which is enforced by radar gun and speed limiters.
"If you are pinged doing over 200kmh you get a 5min penalty," she said.
This will be Gilmour's fourth Targa in the driver's seat and she has co-driven in another three.
As she did in 2005 and 2006 she will compete as part of an in-house promotion with her main sponsor, Vantage.
The company auctions off a ride to their fabricators, so three of them can participate for two days each as her co-drivers.
After the intensity of the 2008 New Zealand Rally Championship, in which she finished sixth, Gilmour enjoys getting out for a blat.
"It's fun because it's a bit more relaxed.
There are fantastic roads and you get to drive fast with no traffic and no cops."
She finished third overall in 2006.
Dunedin's Martin Dippie will also be competing in his Porsche GT3 RS.
Visit www.drivesouth.co.nz for daily updates from Emma Gilmour.
