Replacing 2.7 bi-turbo suspension. what to buy? OEM sports wtd maybe?

Morning. I'm a tourist here from the A4 B6 area so be gentle with me
My mate has a 2.7 bi-turbo quattro A6 C5 and the previous owner has replaced the factory sports suspension with something cheap and nasty. The result was an impressive 60-70mm drop but it's not really practical where we live, plus the rear shocks have now died.
So he's looking for an OEM sports setup, which should be about 20mm lower than standard if it's like my A4. Does that sound about right? Ideally we're looking for a good second hand set of front and rears (probably struts and springs I imagine). There's also an option for a bilstein/eibach B12 Pro-Kit but that's big bucks unless we find a second hand set.
The problem (for me anyway) is that there are so many variants of the C5 that finding anything used is ****** hard.
Any advice would be great. And if anyone knows of a 2.7 bi-turbo being broken then please let me know.
cheers
nj

adamss24 said:

Also breaking a sport avant v6 tdi quattro if that's too low for you, also avant...

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I need to apologise mate. For some reason I didn't see your message waaaaaaay back in May. Possible because I was swamped in work and just didn't see the notification email. I'll check with my mate here to see if he ever sorted this out or he still needs a solution.

erq said:

I recently upgraded from the sport suspension on H&R springs to a Billstein B12 Pro kit. Differance is huge. I always supected my oem shocks we're gone since short speedbumps (you know , the yellow/black tortoises like there called here) would make the car slam on them. With the new shocks the car sits a bit higher but comfort is hugely improved. A little more body roll though, but since it's my daily drive i'm very happy of the Billstein kit.

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Thanks for this. I think maybe my mate bought the car with an aftermarket kit fitted and maybe after a few years of abuse they were failing. In Finland there's only so low you can go before you accidentally because a snow plough too
cheers
nj