Well, I finally went for it. Bought some headers for a 330i off eBay, and got a chance to hook them up this weekend. Initial impressions are great! I think it sound amazing in conjunction with 4.8is mufflers. And, there seems to be a noticeable power bump. I'll post more thoughts once I get to test them more in-depth

https://youtu.be/fjIKys6Dljg

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2004 X5 3.0 6 Speed MT
Build Date - 09/03
156K Alpine White / Black
Premium & Cold Weather Packs, Nav,
Tons of lighting mods, 4.8is Exhaust, Headers, Eibach Springs, OEM 87's, Custom DME Tune, OEM Hitch.

2005 X3 3.0i - 100K - Blue water Metallic / Black

2005 X5 3.0i - 140K - Alpine White / Hellbeige 2