The GM kit looks solid. I spoke to some of the engineers a Camaro Fest (specifically regarding the SS lowering kit + swaybar/link kit) and got the impression they did a lot of track testing to dial that combination in.
Here's info from the accessory guide pointing out lap time improvements:
http://www.chevrolet.com/content/dam...catalog-v2.pdf
SWAY BAR SUSPENSION UPGRADE SYSTEM
Help enhance the handling of your Camaro by adding the Handling Kit to your
Lowering Kit. Includes front stabilizer bar, front handling links, rear stabilizer
bar, instruction sheet and performance emblem.
When combined with the
Lowering Kit, vehicle roll is reduced by up to 18%. Testing on the Milford
Proving Grounds Autocross Course resulted in an average lap time decrease
of 1.6 seconds (overall time
improvement from 1:04.2 to
1:02.6), when also paired with
the Suspension Lowering Kit.
P/N 84242386.
MSRP*: $495.
I don't think most aftermarket companies do this level of R&D on suspension kits.
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2017 Camaro 1SS, M6, Hurst shifter, Hyper Blue, NPP, Gray Split Spoke Wheels
Best 1/4 Mile: 12.24 @ 115.9 mph