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      04-10-2011, 02:23 AM   #6
Rboosted717
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Drives: 2010 X5M
Join Date: Mar 2011
Location: Bay Area

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I finally installed the exhaust earlier this morning.

First off the install couldn't be easier. Honestly this is probably the easiest install I've ever done, especially considering most euro exhaust systems are junk. Every piece of the Akrapovic exhaust system fit like a glove on the first attempt. The stock exhaust is a heavy pig compared to this system.
Oh yeah and the entire stock exhaust system is one piece. Good luck taking it home as one piece. Thankfully I have trailer to tow it home with.

One nuance with the Akrapovic exhaust is the weight of the clamps. With everything being so light, the weight of all eight clamps is pretty significant. And by significant I mean less then 2lbs total.

From start to finish took 1hr 15mins, with the majority of the time spent wiping down the exhaust with WD40 (post install) and aligning/staggering the tips (you could loose your mind adjusting them).

Sound impressions: Very Quite
Reason for being quite: Its not the exhaust, its the stock catalyst. If I hear one more person say this or any exhaust is too quite, I will loose my mind. Even when with the muffler bypass is active (100% free-flow) the exhaust is quite. I don't care what anyone says, no muffler/exhaust will be louder.
The stock X5M/X6M exhaust flows very similar to this system with the difference being the x-pipe and muffler section/ muffler bypass. The main benefit to this exhaust is the weight loss and potential to flow very well with the cats removed (to be installed shortly).

During the install I fired up the truck with open downpipes and was amazed at how muffled/quite the exhaust was because of the OEM catalysts. Given the location (directly behind the turbos) the catalysts suppress almost all exhaust resonance from the engine. The catalysts are the reason why this truck is so quite. No exhaust will cure this unless you remove the cats or switch to very high-flow cats.
I even fired up the engine after installing each section of the Akrapovic exhaust to verify if the sound would become more suppressed and it didn't (no surprise).

Cold start is slightly louder with the normal/warm idle sounding slightly deeper then stock.
Rev'ing the exhaust is also slightly louder with no substantial difference in tone or loudness.
Full-throttle almost sounds stock from inside the truck.
Outside it sounds slightly louder.
Shifts sound almost exactly the same in normal, sport and/or M-mode.
Power wise you won't feel a difference. 10hp is minimal at best on such a heavy and powerful truck. Honestly I would be lying if it said the difference is substantial. Installing an air intake on an E36 M3 produces more noise then this or ANY exhaust on an X5M/X6M.

HOWEVER, I'm 100% positive the results would be very different with the OEM catalysts removed. I've heard the full Hamann exhaust in person (with catalysts removed) on an X6M and the sound is amazing, almost Viper like (especially during cold start). I'm quite certain the sound will be similar if not better when I remove the catalysts. I'm hoping to get that done in the coming weeks when my downpipes are completed.

Below are some pictures during the installation before aligning the tips. I'll post up some rear shots once I wash the truck tomorrow morning.

For reference, here's my current mods:
ESS 91 octane tune
K&N air filters
Akrapovic exhaust
catless downpipes (not installed yet)
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