I haven't seen much about the GT-S systems and wanted to contribute to the collective forum knowledge here - since I would've found it useful had I found something. I spent a while looking across various systems and settled on this. Recently specced and purchased a Brembo GT-S BBK kit (365x34, 345x28mm for easiest 18" wheel clearance)
TL;DR: needed front and rear paired systems with great functionality and support for servicing, plug and play obviously with easy 18" wheel fitment. I also wanted something that wasn't a bright color. After looking at the market options I really liked the Brembo GT-R system with all the features and the nickel finish (Who wouldnt?). Its quite a high dollar system which put it out of my range until I came across a newish? setup from Brembo. Difference between GT GTS and GTR are the pistons, featuring the higher grade heat exchange characteristics and no external dust seals. The exterior finish is a hard anodize black with the classic motorsport Brembo red lettering - which I found appealing. Its GT style body with some bits from motorsport calipers - a hybrid system if you will?
I have more info in my install/project thread
(here) , so I wont pollute with too much stuff here. Also looked at the go-to StopTechs as well as Sparta systems, but balancing pricing, spec, sizing, finish and brand - stuck with Brembo.
Needless to say the build quality is great. The whole setup ends up with an OEM-like look, disappearing into the shadows of the wheel. Braking is now massively predictable, consistent and stable. Modulating brake force is a lot easier with much better feedback from the system. I am very much looking forward to putting these to use on the track once some other bits get upgraded on the car.
