That's pretty much exactly the same setup I'm running. I like the height, makes the car sit much nicer than stock. Here's what it looks like if you're interested.
Handling wise it's good too, I've also upgraded to a 27mm front Falcon swaybar and 23mm rear swaybar. Being a GT there's a possibility yours will already have a 23mm rear bar.
When you put the lowered springs in you can get 'Roll Centre Correction' from Kaplenkhe, although when I tried to do that he screwed me around for about a year as he didn't have them in stock so I just got my money back.