Tried 034 rear sway bar on the home canyon drive and took it right off once I came back.
During those (fairly miserable) two hours of driving I saw more ESP blinking light then over the previous seven years of car's ownership.
Couldn't take a single turn in a mid-spirited manner I'm used to. Basically I had to go way slower to avoid ESP cutting off the power.
I guess I could turn ESP off, but what's the point of loosing rear where it was totally stable with the OEM setup? Won't make me go any faster.
Sent it back to 034 for the store credit (wish they had cash refund option).
IMO it doesn't work with the stock suspension or/and without the stiffer front bar (which they keep saying is not needed - go figure).
I was running "soft" setting - furthermost hole on the swaybar arm.
It's not a surprise honestly - OEM swaybar on US MK6 GTI is 21.7x3mm hollow while 034 one is a solid 25.4mm. I think that's about two times stiffer all other things being equal.
@1ashchuckton, 23mm (+1.3mm) bar would be about 25-35% (if it is solid) stiffer than the OEM 21.7mm. Stiffness of the bar is proportional to the diameter in forth power. I can see 25% stiffer swaybar working.
If you've also swapped the front bar - that would be a totally different story. Because stiffness distribution/ratio between the front and rear bars matters the most.
@theclutch, thanks for the warm welcome and being judgemental, I appreciate it. It certainly helps to have an open and fruitful discussion.
That aside, I'm puzzled myself due to the overwhelming number of positive reviews about that same swaybar. And I do trust 034 as a tuning company in general.
On other hand I saw youtube reviews prizing the bar of making the car handling and ride quality better while driving straight or almost straight (on the highway).
I doubt installation was an issue since there are no two ways to get the rear swaybar installed on our cars. My car setup is completely stock in suspension department and in a good shape. Tires were one year old PS4S and they were not swapped for the 034 swaybar test.
I probably had to turn ESP off in a safe environment to confirm that the rear will indeed step out on fairly trivial turns rather than it being ESP glitch or anything. It certainly did feel that the rear got overly loose. It was indeed night and day difference.