Hey, thought I'd post this up. I modified my bumper shocks on my 1988 325IX to be shorter. After reading all the threads on drilling, watching for danger danger melt your skin off fluid. Drilling while on the car, drilling off and randomly driving into walls here's what I did.
Before

Drilled a small hole to release pressure. There's various reports of internal stuff. I lucked out and got the non-biohazard melt your skin off stuff.

Once the pressure was off, I put a slot in the end of the threaded shaft and turned it out of the housing.

This allows the shock part to be removed from the housing

There's a retaining nut, typical shock type deal here

Removed it


With that off I could pull the piston out

Piston

Looking into the tube

Cleaned the piston and scraped out the stuff (seems like dry silicon)


Reassembled and ready for install

And the difference in extension
Before
Drilled a small hole to release pressure. There's various reports of internal stuff. I lucked out and got the non-biohazard melt your skin off stuff.
Once the pressure was off, I put a slot in the end of the threaded shaft and turned it out of the housing.
This allows the shock part to be removed from the housing
There's a retaining nut, typical shock type deal here
Removed it
With that off I could pull the piston out
Piston
Looking into the tube
Cleaned the piston and scraped out the stuff (seems like dry silicon)
Reassembled and ready for install
And the difference in extension