Edit: SOLD
I bought three of these wonderful pieces to save on shipping and, after installing one in mine and one in a mafia bro's car, I still have one left to sell. Comes with extended subframe bolts, hardware for attaching to the shock towers, and a drilling guide. Super easy install compared to more hidden options and adds some noticeable rigidity to the rear.
https://www.s-m-eng.com/product-page/e46-racp-brace
$675 shipped in the CONUS or $625 picked up in Charlotte, NC. I can also install it if you want to bring me your whip.
I never installed this one, but grabbed this pic when I first received them and test fitted each of them (they all fit perfectly):
Install instructions here: https://30c05fd4-b11d-4ebf-af49-06d1...15d44cf973.pdf