Performance developments / BCS M135i exhaust update

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Performance developments / BCS M135i exhaust update

Post by performance developments » Fri Oct 11, 2013 5:02 pm

Its been a few weeks now since we tested the final production version of the exhaust that we designed in conjunction with BCS Automotive and the good news is that the decats and sport cat downpipes have been a massive success and worldwide sales have been around 5x higher than we had expected!

Having been so busy we didn't have time to do as much work in refining the final details of the catback system that we spent months developing. Yesterday the team met up at BCS Automotive in St Helens and finalised the final design. The look of the system has been altered, the new design uses a slightly smaller tailpipe design with a custom made angle built in to fit the rear valance perfectly (the pics and vids below are of the slightly larger tailpipe)

The biggest problem with the M135i is getting the sound right. Many people will notice that the standard exhaust uses a very small resonator in the rear section under the car that looks similar in size and shape to a catalytic converter. This resonator is there to reduce drone, and with the ECU controlled rear valves, the standard exhaust works well, but as usual with standard exhausts is has been built with many compromises, mainly the areas where the pipework has been 'squashed' to fit through some of the tighter areas of the exhaust tunnel (pictured below). The M135i has a big problem with resonance, some notice it a slight amount on the stock exhaust once it has a few thousand miles on, but with EVERY aftermarket backbox and catback system the drone and deep resonance has been awful, it feels like a horrible vibration through the centre of the car that starts at 1800rpm and dissapears at 2100rpm, its there at light and mid throttle and if you have loose change or keys in the car it will drive you mad, so much so that during testing of these exhaust I actually disliked the car.

One way to eliminate this is to add more silencers, but this makes the exhaust too quiet, so BCS Automotive designed a very special catback exhaust with 3" piping throughout to get rid of the restrictive and unsightly 'squashed' sections and a double valved rear silencer that is controlled via engine boost. At lower boost levels the valves stay closed and gasses are routed through the twin rear silencers that utilise Helmholtz technology that is specifically designed to eliminate the drone experienced with so many other exhausts. The valves open progressively as boost builds , so once the drone has been eliminated you have a fully free-flowing exhaust system that gives optimum performance and sound. The end result is simple awesome, very refined burble during normal driving and No resonance, no drone, no bass, just a fantastic, natural, straight 6 'boosty' wail with a very 'E46 CSL' howl. See the video below!

video link:



'Squashed' stock exhaust and resonator:

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Last edited by performance developments on Fri Oct 11, 2013 6:51 pm, edited 2 times in total.
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godzilla
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Re: Performance developments / BCS Automotive exhaust update

Post by godzilla » Fri Oct 11, 2013 5:27 pm

Very nice.

What wheels are you running on your demo car?
Shadow Edition w/719M wheels, Manual, Estoril Blue/Cognac, full Maxton bodykit, M Perf interior bits,
full Akrapovic, M4 LCAs, Quaife

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Re: Performance developments / BCS Automotive exhaust update

Post by performance developments » Fri Oct 11, 2013 5:29 pm

VMR 19" V710
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Re: Performance developments / BCS Automotive exhaust update

Post by copperman05 » Fri Oct 11, 2013 5:42 pm

Very nice Mark.

Do you have prices for sports cat and DP?
Present: M235i, Melbourne Red.
Past: M135i, Mineral Grey, 428hp 481lbft

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Re: Performance developments / BCS Automotive exhaust update

Post by performance developments » Fri Oct 11, 2013 5:46 pm

Sports cat downpipe is a 200 cell unit and costs £599
Decat will be £269
Performance Developments - Sedox ECU remaps - European dealer for JB4 systems - VMR Alloy Wheels - Milltek BCS and Remus exhaust systems - 4wd 2400bhp Dyno Dynamics Rolling road

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Re: Performance developments / BCS M135i exhaust update

Post by Arrow29 » Sat Oct 12, 2013 3:06 am

Looks and sounds great. Ensuring no drone is a big plus and I'm impressed with the efforts you guys have gone to to eliminate. I'm quite happy with my stock car currently as it's only a couple of weeks old (and already sounds a million times Better than my RS250) but down the track when I'm sure I'll want a change yours will be the one I go for!

Is that video the cat back only or with the sports cat/dump pipe as well? Wondering if the addition of the DP/sports cat would make it louder again.




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Re: Performance developments / BCS M135i exhaust update

Post by performance developments » Sat Oct 12, 2013 9:28 pm

The addition of a Sports cat or decat does make the exhaust sound a little louder and more aggressive, but unfortunately also introduces drone.
Performance Developments - Sedox ECU remaps - European dealer for JB4 systems - VMR Alloy Wheels - Milltek BCS and Remus exhaust systems - 4wd 2400bhp Dyno Dynamics Rolling road

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Re: Performance developments / BCS M135i exhaust update

Post by Arrow29 » Sat Oct 12, 2013 9:56 pm

Hmm would the majority of performance gains come from the sports cat down pipe or the cat back system, in your experience? I've always been under the impression that changing the down pipe brings the biggest gains in a turbo but correct me if I'm wrong.


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Re: Performance developments / BCS M135i exhaust update

Post by Blind Pugh » Sun Oct 13, 2013 8:33 pm

Depends on who speak to.

The majority will say that DP will bring the more gains than a cat back exhaust.

However, some manufacturers ie Scorpion claim, in their M135i exhaust video on YouTube, double the gain from the cat back than their hi flo cat DP.

I had hi flo cats on my E91 335i and this alone gave me an extra 17 Bhp, compared to baseline with oem DP's. Doubt v much an exhaust system would get double digit improvements.
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Re: Performance developments / BCS Automotive exhaust update

Post by fredo » Mon Oct 14, 2013 11:52 am

Where do I find the info reg. the DP on your homepage?
http://www.performance-bmw.co.uk" onclick="window.open(this.href);return false;
performance developments wrote:Sports cat downpipe is a 200 cell unit and costs £599
Decat will be £269

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Re: Performance developments / BCS M135i exhaust update

Post by performance developments » Mon Oct 14, 2013 12:03 pm

its all being added during this week, available to order now by phone but we are just waiting to take photos and make a new web page for the M135i exhaust components.
Performance Developments - Sedox ECU remaps - European dealer for JB4 systems - VMR Alloy Wheels - Milltek BCS and Remus exhaust systems - 4wd 2400bhp Dyno Dynamics Rolling road

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Re: Performance developments / BCS M135i exhaust update

Post by performance developments » Mon Oct 14, 2013 12:06 pm

Arrow29 wrote:Hmm would the majority of performance gains come from the sports cat down pipe or the cat back system, in your experience? I've always been under the impression that changing the down pipe brings the biggest gains in a turbo but correct me if I'm wrong.


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Neither will give a great deal of gain without tuning, but now that our exhaust has done about 1000 miles we will be testing the output on stage 2 with full exhaust when compared with our findings from stage 2 with just downpipe.
Performance Developments - Sedox ECU remaps - European dealer for JB4 systems - VMR Alloy Wheels - Milltek BCS and Remus exhaust systems - 4wd 2400bhp Dyno Dynamics Rolling road

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Re: Performance developments / BCS M135i exhaust update

Post by fredo » Mon Oct 14, 2013 12:26 pm

Will the BCS BB have an EU approval?
and will the DP be combinable with the Milltek BB and original mid section?

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Re: Performance developments / BCS M135i exhaust update

Post by Arrow29 » Mon Oct 14, 2013 2:56 pm

[/quote]
Neither will give a great deal of gain without tuning, but now that our exhaust has done about 1000 miles we will be testing the output on stage 2 with full exhaust when compared with our findings from stage 2 with just downpipe.[/quote]

Awesome, I look forward to seeing the results



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Re: Performance developments / BCS M135i exhaust update

Post by performance developments » Wed Oct 16, 2013 3:00 pm

will post soon, dyno is pretty much booked up at present.
Performance Developments - Sedox ECU remaps - European dealer for JB4 systems - VMR Alloy Wheels - Milltek BCS and Remus exhaust systems - 4wd 2400bhp Dyno Dynamics Rolling road

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