You’re probably better off with a higher end lowering spring than buying $650 coilovers... are you just looking for lowering? Because a $650 coilover from an unknown brand sn’t going to give you any performance whatsoever.
RS-RR are some of the noisiest tires I've ever heard. The new RS-Pro are being marketed as an updated RS-RR with less tread noise. I don't have experience with them, but I have a friend with the RS-Pro, and he loves them.
We don't have E content/FlexFuel yet on our platform. That picture was posted by a troll who doesn't even own a VAG car, that trolls around our forum because he got banned from his Subaru forum for saying repeated racist/xenophobic things, and general asshat-ery
It is debatable, as different tunes and tuners seem to have a different consideration of what is an acceptable amount of KR. Ideally you want 0 KR, but different situations will generate KR much of the time - accelerating uphill, high load, etc. For reference, my finished dyno tune has 0 KR at...
If you're running a file that needs revisions, definitely monitor Knock Retard for all 4 cylinders like Diggs said. If you're on a finished/base tune file that is safe(r), you can just monitor KR average. I monitor relative manifold pressure, oil temp, KR average, accelerator position, and AFR*.
I've asked TPC for real dyno graphs, etc. from tuners/etc. for the TPC20 and TPC38 to show spool(since the spool on the ones they advertise is terrible, especially for an is20 based turbo), and their response has basically been "they are out there". Do you happen to know where one can find any? haha