Hi,

Relatively new owner of a 2015 Q40 AWD, which is pretty much a G37x. This review isn't that detailed, but more of a notice to Q40 and/or AWD owners that these parts fit fine. I had been driving an IS300 Sportcross outfitted with Koni yellows and an Eibach spring/sway kit for the last 17 years. The car handled like a go kart, and i needed a bit of that feeling from the Q. Stock, the Q is pretty sloppy. Tons of body roll and the OEM tires are terrible. I ordered a set of Bridgestone RE980s from Costco. I wanted to stay with the stock 17" wheels so these are a great all season choice. Immediately the car handled better, but it was still rolling heavy. I had a shop install the Swift Springs and Cusco strut bar along with a full alignment and underbody inspection. My son and I installed the Stillen rear bar and Bell brace. The car handles really flat now and has that nice rotation feeling in turns. Stillen claims the bar does not fit AWD, but that is because it is sold as a front/rear pair and the front definitely doesn't fit. The Stillen is 25mm diamter vs 17mm OEM so I bought Energy Suspension bushings and brackets. I used the stock end-links and greased the new bushings with Mobil1 synthetic grease. The diff brace was easy to install. Did both while the car rear was on ramps.



Stock, note the wheel gap.



After the Swift install, much less gap, but not a crazy drop.




Stillen rear bar vs OEM.....lol




all the new red stuff. Swift springs, Bell brace, and Stillen sway bar.

 

Any updates on how the car handles compared to stock and if the comfort level has changed at all?

 

Keep an eye on the rear end links, the OE parts aren't up to the loading of a stiffer bar.

 

So I upgraded my X to the OEM S rear sway bar. It is 24.2mm, does the S have different end-links than the X? Does the 0.8mm difference in the Stillen really enough to break the endlinks?
Iirc the Stillen is also adjustable, maybe this contributes to the stress on the endlinks.
Would love to know.

 

In truth, it's lowering the car that kills the stock rear end links. Mine blew the day I had coil-overs installed. I was also running the Hotchkis bars set at soft.

 

The car handles great. Very confident in high speed turns. I only run into issues when I run into extreme road surfaces (big potholes, speed bumps, large undulations, railroad tracks). At those times you can tell you are under-shocked. I'm still running the stock shocks. Waiting to see how the Koni inserts for the AWD thread works out.