I've done my bags 4x now, couple of mistakes I have made.
If you do one, do both. The rubber at the creases deteriorates and they both will fail around the same time.
When removing, lead with the top while removing instead of moving bottom of bag out first. Once the bottom is detached turn bag to unlock top and push the bottom towards the rear differential. This will expose the top and allow you to unscrew air line and then easily remove the bag.
Do not retighten the air lines at the pump after you deflate. You will need to expand the new bags once in place and if you have tighten the air lines this will nearly be impossible.
Make sure you click the lower in place.
Validate proper inflation once inflated.

As an fyi, stan's no tubes sealant will seal any leaks. Had to use it in a bind while waiting for shipping and actually the bag held for 3 months.
Careful with the brass compression fitting, they will split in half if reckless.

I just changed my rear driver side airbag but now I'm having second thought of not replacing the other side. When I park my X on somewhat of an incline at work, the rear passenger side is sagging close to the tire but does go up while driving. Dealer charged about $400 for the one side.

Should I just fix the other side even though it's not poped?

Yes, get it replaced right away...but why get replacements from the dealer? Arnotts would supply both left and right rears for just under $400 if I'm not mistaken. And since fitment is really no more complicated than following a very simple "how to" instructional video on their website there's no reason not to DIY.

If you don't have the proper tools including jacks and stands it's not worth the effort. $400 is pretty respectable considering.nwonder why they didn't try to both.

Considering they are $160 per side on Amazon, and this is about a 2 on the 1 - 10 difficulty scale for DIY, I'd opt to save some money and DIY. I don't like paying for stuff I can do myself.

Arnott air spring users, do you have to remove the brass nut that came already installed in the new bag off and reused the brass nut on the air supply line?? Or do I just insert the air supple hose only to the new arnott bag??
Thanks, Sam

Sam, best advice I could offer is to have a look at the video instruction on the Arnott website. I used everything supplied in the kit so if they had supplied new ferrules and nuts then I would certainly have removed the old ones.

On the arnott installation video, it says to toss out the old air supply line brass fitting on the old bmw bags and just insert the air hose. Is this right?? Also the instruction say to insert the air hose and gently pull it. When I do that the air hose pull right out, there nothing stopping it from pulling out. Is this normal?? Thanks, Sam

This is NOT correct Sam. It's been a while since a replaced mine but I'm certain the airbags where supplied with new brass ferrules. The reason you are instructed to gently tug on the lines is to make sure you've correctly fastened them to the bags...which will be impossible to do without the ferrules (brass retaining rings) so if you didn't get any in your kit then I hope you have not thrown your old ones out because you will have to reuse them.

The bags came with the brass nut already installed. But I didn't see the little brass locking nut inside. While watching the installation video, I didn't see them taking out the brass nut when they were installing the air hose. Does this mean I have redo it?? Thanks, Sam