Hello my fellow e53 brothers. It's been a while. Having installed headers on my 3.0, however anecdotal, the old butt dyno felt quite a difference in performance and the sound is just shaweeeeet. The stock exhaust manifold with integrated cats is not optimal for performance. Bmw crammed the cats up high and close to the heat as possible to get them up to temp faster, to help make the m54 ULEV. I've posted picsl/vids in my other threads. They're quite compromised. I've also ran with open headers for a few days. There seems to be a loss of torque down low, but mid range and top end was awesome. Once I hooked the rest of the exhaust up, it was better down low and pulled much harder all the way to red line.

Just a note. I had shark injector software w/ the 7 k red line, modified exhaust with oem center muffler/resonator in place, and rear muffs replaced with some magna flow resnators welded in.

My X gets inspected this week, and then my headers are being installed soon on my current e53. I was going to do it over the summer, but I wanted some time to sort out aftermarket cats and Euro 2 software tune to delete out the post O2's.

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2005 X5 3.0, 6MT, Alpine White on Truffle Brown, Sport, Preim, and Cold Weather, Alpina Stainless Headers, AFe Intake, UUC SSK, OEM 87's, 3.64 Differential Swap,Performance Modified Euro 2 Tune, UUC LTW Flywheel and HD clutch, Bilstein B12 Suspension kit
Future mods ZHP/Schrick Cam Shaft upgrade, Operation code name:Doppelschrauben-Kompressor

Wife's Ride: 2011 e70 X5 351 M///Sport.

Also in the fold: 2004 X3 3.0, 6MT, Black Sapphire on Terracotta, port, Premium, Cold Weather.