Did you also do poly for the subframe bushings? If so, how does it ride?

I am also curious how the poly bushings in the rest of the suspension changed the overall ride quality, given how you have an MT as well. I guess I am hoping it make it more sporting.

I have the sport suspension on my 5mt and it seems to ride kind of stiff, even with 18 inch wheels.

Yes, I also did poly subframe bushings. With my BC Racing coilovers set to 0 and the bushings, it doesn't really ride any stiffer than the stock sport suspension (which was already stiff imo). When throwing it in the corners it's very composed and pretty fun to drive. It's a lot closer to a car than the SUV it was before.

I may be needing to borrow the rear ball joint too in the coming months, I'm approaching 100k and only the subframe bushings (Meyle HD) and rear sway bar bushings and links have been done -

After my 4 corner brake overhaul I think its on to the rear suspension, front was done about 20k miles ago

You've got my info!

Your biggest challenge with the front end stuff is going to be the front tension arm ball joints. They suck! Pre-soak them good, and be prepared to have the blue tipped wrench at the ready. It took me (don't laugh) 6 hours for the driver's side and 4 hours I think to get the passenger's side off. They like to literally freeze/weld/corrode themselves into the knuckle.

Other than that it's pretty straight forward stuff. Best of luck to you.

The FCP kit you mentioned above is very good.
It is all Lemforder.

I wrote a very detailed DIY REAR and FRONT suspension overhaul for my E39 1998 528i on bimmerfest.

Anyway, the DIY REAR suspension overhaul for my E39 1998 528i, which is very very similar to E53 X5, is below:

DIY: 1998 BMW 528i Complete REAR Suspension Overhaul - Bimmerfest - BMW Forums

Thx Crystal, check this out. It looks like a life saver in those kind of situations:
https://m.youtube.com/watch?v=_YO_snrzYrs

Thanks Cn90 I have used your DIY as a reference in the past.Very detailed and easy to understand.
Matter of fact, last night when I torqued down the top strut nuts I was looking for the torque values and used your picture for reference.
Thanks again!

^Wow. I don't want to know how much that costs because in my head I'm telling myself it's too expensive to justify replacing the good old torch. ;)

Around 450$
Nice thing is they have attachments for pretty much every size bolt, bearings etc
Made in USA
LOL I sound like I work for them.