I called Tanabe and found out the Q50 rear sway bar will be released in a couple of weeks.
What I found interesting is the Q50 front sway bar shares the same part number and is technically the same part TSB150F as the front sway bar Tanabe offers on the G37.
Here are some pictures from the Tanabe site comparing the sway bars on the Q50 to G37:
We test fitted the Tanabe Sustec Front and Rear Stabilizer Bar on 2014 Infiniti Q50S (RWD). The sway bars help increase steering response and stability.
Q50 Front (TSB150F) and Rear Sway Bar (??????)

Front Sway Bar Installed on Q50
G37 Front Sway Bar (TSB150F)

Front Sway Bar Installed on on G37

G37 Rear Sway Bar TSB150R (arms looks shorter)

Installed on G37
The person I spoke to at Tanabe said the rears might be different for the Q50, they are waiting on more information from Tanabe in Japan in a couple of weeks.
This would mean quite possibly both Whiteline and Hotchkis G37 front sway bars may fit on the Q50 now.
Whitelines are adjustable:
BNF41Z
Front Sway bar - 27mm heavy duty blade adjustable
This Whiteline 27mm 2 point adjustable sway bar = more grip = better handling = outright performance - it's the best dollar for dollar handling improvement you can make to your vehicle. This Whiteline...
2 point adjustable
US $ 259.80
BNR37Z
Rear Sway bar - 24mm heavy duty blade adjustable
This Whiteline 24mm 3 point adjustable sway bar = more grip = better handling = outright performance - it's the best dollar for dollar handling improvement you can make to your vehicle. This Whiteline...
3 point adjustable
US $ 239.80
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G37 Whiteline Installed on a G37
FRONT SPECS:
Part Number: BNF41Z
27mm heavy duty blade adjustable
Note: This Whiteline 27mm 2 point adjustable swaybar = more grip
Key Feature and Benefit
This Whiteline 27mm 2 point adjustable swaybar = more grip = better handling = outright performance - it's the best dollar for dollar handling improvement you can make to your vehicle. This Whiteline adjustable sway bar allows its rate to be altered by increasing or reducing the length of the lever arms. This permits the roll stiffness to be tuned for different situations without replacing the entire bar. The stiffer the bar, the more force required to move the left and right wheels relative to each other. This increases the amount of force required to make the body roll
Features and Benefits
Whiteline Sway Bars
The fitting of bigger Whiteline swaybars is still the best dollar for dollar handling improvement you can make. Cornering loads are spread more evenly across the tyres delivering more grip and frankly, that’s what it’s all about. You also get improved tyre wear as your tyres stay flatter and more upright. Comfort improves because your car sits flatter through bends meaning less movement inside the vehicle. Whiteline swaybars are manufactured using the finest grade spring steel. They are powder coated and supplied with high performance polyurethane mounting bushes in a DIY kit form, ready to simply bolt on.

Retail price $271. Pm me for pricing
REAR SPECS:
Part Number: BNR37Z
Description: Sway bar - 24mm heavy duty blade adjustable
Note: This Whiteline 24mm 3 point adjustable swaybar = more grip
Application Notes
Part Notes
Replacement type
3 point adjustable
Key Feature and Benefit
This Whiteline 24mm 3 point adjustable swaybar = more grip = better handling = outright performance - it's the best dollar for dollar handling improvement you can make to your vehicle. This Whiteline adjustable sway bar allows its rate to be altered by increasing or reducing the length of the lever arms. This permits the roll stiffness to be tuned for different situations without replacing the entire bar. The stiffer the bar, the more force required to move the left and right wheels relative to each other. This increases the amount of force required to make the body roll
