I've been thinking about replacing my rear air springs since there original & I'm replacing bushings in the rear suspension already.

From what I've been reading is that the subframe needs lowered to install oem style air springs, but why?
If the bags come out with lowering the subframe, why can't the go back in?

I'm assuming it has something to do with the larger hose connecting to the top of the oem spring since Arnott bags don't have this hose, but it looks like it's easy enough to dis or connect to the air spring.

I just don't see what the issue is but obviously missing something.
​​​​​

It does not need to come out to swap them. Making sure they are COMPLETLY deflated is key to removal .

Can they be deflated with a 9v battery like the front?
Any other tips or suggestions?

What is the purpose of this canister & hose?

When installing OEM style air springs, it's generally recommended to lower the subframe 1-2mm to ensure proper clearance between the air springs and the control arms. This prevents premature wear and maintains even ride height. Lowering the subframe also helps with proper air spring alignment, which is crucial for optimal performance and durability.

Comfort mode. Additional air volume lowers the pressure and softens the ride.
And getting the cannisters into the rear subframe is why WIS shows lowering the subframe. One of the reasons I went with Arnott.

I always forget....when working at a flat rate shop.....we cheated as much as possible to speed things up and lowering a sub frame I would always want to align the car just to make sure it was straight and that was more time I didn't have in the day. So yes than do what bbirdwell said if you want to do it correctly and by the book,thats your best bet.
I can't tell you how many dash boards had to be completely removed by the book and we where able to pull it back to do what ever needed done and save on our work load....and of course make more money.