Yes. Do the M3 rack. It's just better, unless you really hate any steering resistance when at a standstill!
I might have to keep an eye out for one of those chassis braces. (EDIT - Just seen yours is an e91 too!
) Mine, being the e91 already has bracing to an A frame behind the rear subframe, from just in front of the rear subframe front mounts...I wonder if the e84 brace would be retrofittable in this case - looks like the 2 need to overlap. Where did you get yours, and how much did you pay, if you don't mind me asking?
Camber using a spirit level. I was inspired by someone who installed an M6 x 1.0mm bolt into a spirit level to use as a camber gauge. The pitch is 1mm, so every turn of the bolt is 1mm of progress. From having the bolt flush with the level surface, adjust the bolt until it reads level, while counting the turns. Or use a vernier to measure the bolt protrusion.
I didn't exactly do that though - my way is less accurate, but doesn't involve modifying a spirit level... I just offered the level up to the wheel, and directly measure the gap between the wheel rim (or whatever your contact point is - mine was actually the tyre bead) and the level, when the level is vertical. Then high school trig (tan^-1) to figure out the angle from the offset measurement, and the distance between the 2 level contact points. Because my car wasn't necessarily level (not on even ground), I used a couple of bolt heads just in front of the bonnet catch as a datum. Certainly not the most accurate point to measure from, but I was just in need of some sort of reference. I'd say it's accurate enough, having registered 0.45deg change on one side and 0.46deg on the other!
I haven't calculated toe yet...it's close enough for me, though I might get the string out again and measure it properly since I'll probably have a lot more free time what with Covid. I'll use the same method though, just string instead of spirit level. And I'll need to reasonably accurately measure track width F&R too... I think yours is a bit off. I'd expect <1mm per wheel, off the top of my head.
