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      01-13-2013, 01:13 PM   #1
pwn
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Exhaust sizes for N55? 2.5"? 3? 4?

I haven't seen any documentation anywhere stating current exhaust measurements for the N55. I see people mentioning their DP goes down to 2.5", they have the AR 4", etc. What size is the inlet to the midpipes, and the outlet from the midpipes into the catback?

I come from a subaru where 3" all the way was sufficient. I also haven't really seen any midpipe replacements for the N55. I saw some guy mentioning he had the Berk catted mids on his N55, but I don't even see them for sale on their website unless its the N54 system?

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Morgan
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      01-13-2013, 01:51 PM   #2
WhiteTgr135i
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I came from a Subaru as well, but I was running a 4.5 inch turboback exhaust on my car considering I was running a huge turbo.

For the 135i, the midpipe size, 2.5 / 2.75 is more then efficient when it come to power. Since our cars run a single outlet exhaust, a dual midpipe is pretty much useless.

The main power source is our downpipes. Our oem downpipes aren't free flowing at all, plus they weigh a ton.

If you want to see some results, swap out the downpipe. For our cars, the n55 runs strong with a 3.5inch downpipe or 4inch. Hope this helps.
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      01-13-2013, 02:20 PM   #3
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Berk midpipes are resonated, not catted. N54 guys swap to berk or N55 mids. So get a down pipe for power and if you want a more aggressive sound go with a cat-back that has a muffler.
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      01-13-2013, 04:18 PM   #4
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I guess what I'm really getting at is what size the Y pipe to the twin mid pipes is? If I get a 4" downpipe, do I need a flange down to 2.75? or 3? Whats the size on the other Y going from the mids to the axleback?

Thanks!
Morgan
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      01-13-2013, 06:00 PM   #5
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Someone correct me if I'm wrong, but it seems all the aftermarket exhaust parts are compatible. IE; I have not heard of anyone having having one DP not fitting another companies mids or axel back. I think piping sizes vary but all the major companies keep the same size flanges. Does that make sense?
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