Exhaust Diameter e87 (2005)

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Manufactured from 2004 to 2011

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Pabzy
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Exhaust Diameter e87 (2005)

Post by Pabzy » Sun Nov 05, 2017 12:31 am

Evening all,

I am due to have a custom exhaust fitted and Im undecided on what is the best size centre pipe diameter. I was thinking 2.5" maybe? (Larger than stock and enough to get more power out of the 120d). It will be from the cat back (no DPF on my car) straight through with one centre silencer and out into a twin 3" pipe. Not after anything loud so felt that with the one box it will be slightly louder then OE.

I know a lot of people rave about the milltek system which has a 2.75" diameter but I have heard other people say its too big for a 120d. Im not clued up on differences that the size makes but think the standard diameter is 2"? I will be getting the car remapped soon after the exhaust has been fitted and hoping to hit the 200bhp mark :spotman:

What do you think guys. Is 2.5" enough or do I need to go bigger?
Last edited by Pabzy on Sun Nov 12, 2017 9:06 pm, edited 1 time in total.
2005 120d. Sydney Blue, Xenons, Black Grills, 18" Deep Dish BBS, Drilled brembos, Tints, LCI Heated Leather, CDV, Swirl Flaps & EGR gone, M Sport interior goodies, Prof HU, HK Subs and Speakers. Time to make it move! 8)

Pabzy
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Re: Exhaust Diameter e87 (2005)

Post by Pabzy » Sun Nov 05, 2017 12:33 am

Anyone?
2005 120d. Sydney Blue, Xenons, Black Grills, 18" Deep Dish BBS, Drilled brembos, Tints, LCI Heated Leather, CDV, Swirl Flaps & EGR gone, M Sport interior goodies, Prof HU, HK Subs and Speakers. Time to make it move! 8)

mini bmw
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Re: Exhaust Diameter e87 (2005)

Post by mini bmw » Sun Nov 05, 2017 3:56 am

its 2.2"
i think
BMW 120d sport e87 163bhp

pem10
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Re: Exhaust Diameter e87 (2005)

Post by pem10 » Sun Nov 05, 2017 9:30 am

I would have thought Milltek know there stuff so I'd be copying them personally. Who says it's too big?
130i se. Sparkling graphite metallic. Xenons darklines bmwp intake and roof spoiler. Now with added 313 goodness.

Pabzy
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Re: Exhaust Diameter e87 (2005)

Post by Pabzy » Sun Nov 05, 2017 5:45 pm

Few of the other forums commented that it may be too big for a 120d. The quote below talks about a 123d so also figured anything above 2.5" would be too much for a pre fl 120d??
Rjudgey wrote:
Tue Aug 18, 2009 5:28 pm
Smokey! shouldn't smoke too much mine has no DPF was only an option at the time. Mines running 215bhp and 300lbft without the exhaust, and as far as turbo's go the least back pressure the better obviously dropping a huge pipe size on might not be so advantageous as you need to get the size right for the turbo, too big a pipe you loose velocity and power, too small too much back pressure and not much gain in power. I think 2.75" is just about right or maybe 3" at the most if you have 123d.
2005 120d. Sydney Blue, Xenons, Black Grills, 18" Deep Dish BBS, Drilled brembos, Tints, LCI Heated Leather, CDV, Swirl Flaps & EGR gone, M Sport interior goodies, Prof HU, HK Subs and Speakers. Time to make it move! 8)

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Conor118dmsport
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Re: Exhaust Diameter e87 (2005)

Post by Conor118dmsport » Sun Nov 05, 2017 9:58 pm

I had a custom exhaust made from cat back and no boxes at all, 2.76” pipe all the way to a 3.5” twin pipe. Not loud at all sounds nice


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Conor118dmsport
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Exhaust Diameter e87 (2005)

Post by Conor118dmsport » Sun Nov 05, 2017 9:59 pm

I had a custom exhaust made from cat back and no boxes at all, 2.75” pipe all the way to a 3.5” twin pipe. Not loud at all sounds nice


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Pabzy
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Re: Exhaust Diameter e87 (2005)

Post by Pabzy » Sun Nov 05, 2017 11:49 pm

I suppose the loudness is subjective as to what someone deems to be loud. Last car was fairly loud (MK1 Golf GTI on twin 45 Webber Carbs :band: ).

All I am bothered about is what size diameter pipe is best for the size of turbo the 120d has and of course the benefits of a remap. I am puttting in a centre silencer to keep the sound close to OE however my main aim is to increase the performance in line with what is realistic for a mapped 120d. 200 bhp I feel is acheivable. I didnt think this sort of BHP warranted a 2.75" or 3" centre pipe? Would it not be detrimental rather than beneficial if it was too big?

For example, the 335d tends to run 2.75" / 3" centre pipe diameter however they produce nearly twice the power when tuned therefore justify the larger pipe. Didnt want to go 2.75" as this is more 123d territory like the Milltek exhaust set up.

What has everyone else got on their 120d's?
2005 120d. Sydney Blue, Xenons, Black Grills, 18" Deep Dish BBS, Drilled brembos, Tints, LCI Heated Leather, CDV, Swirl Flaps & EGR gone, M Sport interior goodies, Prof HU, HK Subs and Speakers. Time to make it move! 8)

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