Re: E60 Exhaust Manifolds
Just fitted Hiop headers from Juzz4Cars. Phew..! The car suddenly feels so much lighter and the exhaust note...wah… To get maximum benefit from this setup, it’s advisable to change your rear muffler too. I’m on a Remus back box as I prefer to sound to a supersprint.
Anyway, make sure that you change the middle resonator. Due to the increased flow, the plates in the Resonator will rattle and you get a really irritating resonance at 2000 rpm.
The only solution to this will be to replace the resonator with an absorptive silencer (aka hotdog) but beware, because the BM’s exhaust temperatures are unusually high, the filling in these "hotdog" usually either fly out or harden within a really short period of time.
Another solution would be to cut out the resonator completely but this is not advisable unless you want to tell people you are coming a mile away.
My solution is actually to operate the original resonator. Due to the space constraints and the lack of already little ground clearance, I am in the process of taking the original resonator down and cutting it open. I would then fabricate a y piece to convert the two 2” pipes from the manifold to a single 3” pipe (same as original arrangement). Remember to perforate this y piece for the exhaust gas to react with the filling to attenuate the sound. Inside, I will fill this with my secret recipe of stainless steel shavings and wool. This is to dampen the sound and since this is an absorptive silencers and not a reactive one with plates inside, it wouldn’t vibrate like the original item.
Can’t wait to do it and hear what the end result will be.