Akropovic Evolution Exhaust

[kimbow]

Hi all, I have had the Akro Evolution exhaust on my E92 M3 for a while now with an ECU remap to prevent check control light coming on. I want to fit the exhaust to my new E92 M3 but dont want a remap due to possible warranty issues. (I know fitting a non OEM exhaust could potentially raise warranty issues but I would remove it before I took it for any serious warranty work)The delete r module you can get for this system does solve the check control light issue without remapping but is around £300. Question is if I fit the exhaust is a remap needed purely to address any performance issues due to the nature of the primary cat delete, or is it fine with no ECU changes and just a delete r module to stop check light coming on. Thanks to any wizards out there who know the answer to this.

[Hair Flick]

Remap not required and I would imagine all the old map did was disable the CEL....

[kimbow]

Thanks, thought that might be the case. Some 'tuners' say you need a remap to compensate for changes to low end torque but I suspect that is a ruse to charge you £500 to switch the rear lambda sensors off !!

[Hair Flick]

They are just a ruse. The ECU is more than able to compensate for any increase airflow an exhaust will give, most if not nearly all these tunes do is turn off the CEL (but the error remains within the memory so come warranty time if its as a result of a cold o2 sensor well good luck with the arguments if BM want to argue) and remap the throttle position, similar to when you press the sport button on the e39.

Modern ECU's monitor airflow, intake temp and some monitor exhaust AFR if they have widebands installed. Changing from the cats back will have an effect but hardly outside of the parameters the ecu can handle. removing cats, changing headers then potentially you would want to map.

I really fail to understand why anyone would pay to remap a naturally aspirated car, especially an M car. I used to create tunes and on some cars that came seriously detuned from the manufacturer you got great gains but on the majority of cars the maps are pretty good. Ok optimised these days for the fuel and emissions tests so some flat spots can be removed but M cars will be pretty close to optimum. Most BHP is gained towards the end of the range and unless you are getting at least a 10 to 15% gain it isnt worth it. I've seen folk spend thousands only to gain 8 to 10 bhp which at vmax events equalled zero advantage over stock.

[omniflow]

Hair Flick said:

I really fail to understand why anyone would pay to remap a naturally aspirated car, especially an M car. I used to create tunes and on some cars that came seriously detuned from the manufacturer you got great gains but on the majority of cars the maps are pretty good. Ok optimised these days for the fuel and emissions tests so some flat spots can be removed but M cars will be pretty close to optimum. Most BHP is gained towards the end of the range and unless you are getting at least a 10 to 15% gain it isnt worth it. I've seen folk spend thousands only to gain 8 to 10 bhp which at vmax events equalled zero advantage over stock.

You've answered your own question in that paragraph.

One reason why people might remap a naturally aspirated car is so that when they go to a Vmax event the speed limiter doesn't get in the way.

So far I have not been able to find anyone who will JUST remove the speed limiter on an E60/61 M5.

[Hair Flick]

True but you could go to BMW and pay to have the limiter removed....

[kimbow]

Thanks for taking the time to respond gents, your comments are most welcome. I will consider your wise words and the way forward from here.

[Hair Flick]

kimbow said:

Thanks for taking the time to respond gents, your comments are most welcome. I will consider your wise words and the way forward from here.

Without E92 knowledge I am not sure what this exaust does and what the CEL light is triggered. If its post cat O2 sensors well the easiest thing is to relocate those closer to the cat as 9 ot of 10 times the trigger will be a slow response.

If its pre cat sensors that trigger because the aftermarket exhauts move them futher away from the engine then the same is true, so easier to always keep o2 sensors as close to their original locations.

if its a decat system then good luck, I wouldnt bother with one for anything but the road. Most CEL from afermarket exhausts result as moving the o2 sensors so they do not get to temp as fast as the car expects so a CEL is thrown.

Decats are pointless, a few ponies for a lot of issues come MOT time or legality if unfortunate to be spot checked at the side of the road. You get those that argue as long as you pass the emissions you are fine, well type approval for all cars since 93 required a cat. I;ve ran bypass pipes, measured before and after results and they were negligable. Getting away from the point.

What is this £300 option that isn't a tune but fixes the problem? Because if its just relocating the sessors any decent local exhaust place will do it for a fraction of that cost.

The best mods for exhausts, if just for sound, is resonator deletions, modifications and perhaps slipping in an x, h or kiss pipe

[kimbow]

The delete r is an electronic device piggybacked on the OBD port, it fools the ecu to stop the cel light coming up. The primary cats are deleted on the Akro evo exhaust and this is where the two o2 sensors are, hence the cel light coming on. Akra advise the delete r is not the best solution and advise a remap to cure the problem. TBH on a new car I think I wont bother with the Akra Evo, may just sell it and go for the Akra slip on system which is just the rear boxes so no cat deletion or gas flow problems

[Hair Flick]

Any trickerly like that is not a good idea and a costly one at that with the price quoted! So it does delete cats, oh well. Look the deal is that all that you are doing when removing the cats is just that, it makes next to the square root of nothing to the performance. It can increase noise but seriously the cats are not a major restriction and if they are, replace with high flow cats and just replace them more frequently.

Do exhaust work post cat and you can release the noise without upsetting the cars electronics or systems. The remaps of which they speak will offer you an extra 20 to 40 bhp and a packet of magic beans along with a nice little set of CEL triggers. Personally I would like to get an alert that my O2 sensor is not working correctly as I don't trust "friendly" MOT statons that will pass anything they see.

There are some reputable tunes out there that will give a real increase but I would only ever validate this by using an indipendant RR such as Surry Rolling Road, the owner there has bad hair but is consitent and knows how to run a dyno and a clean bathroom. But a map from an exhaust manfucaturer, I'd put it up there along side SuperChips and Bluefin.

eta not sure why I want all Japanese at the beginning but seen you are going for slip ons, thats what I will be doing or some slip on cut outs so I can go quiet when I want to.

Edited by Hair Flick on Friday 1st March 19:25

[kimbow]

Yep, I think slip on rear box is the way forward to release the V8 noise but not mess with the cars management systems. Thanks for your input.

[cs1874]

kimbow said:

Yep, I think slip on rear box is the way forward to release the V8 noise but not mess with the cars management systems. Thanks for your input.

I've been going through the same headache trying to choose between the Evo full system or the Slip-on rear system. I didn't know there was any jiggery pokery required when using the full system...the Akra distributor certainly didn't mention it....this has probably made up my mind to go for the Slip-on system....Oh yeah.. and save myself a grand in the process!!

[kimbow]

Yes its a bit of a conundrum !! The slip on does sound nice but wont give the performance gains of the full Evolution system. However the trade off is no messing with the slip on, fit n go. The full system does need ECU map change or delete r module (£300 !!)to stop the cel light coming on and for a slight low rpm torque dip,(according to Evolve) due to the faster gas flow, as the primary cats are deleted ! The exhaust supplier should have told you this as you would have had problems if you thought the Evolution system was plug n go ! Anyway, a grand saved to spend on something else for the car !

Edited by kimbow on Sunday 3rd March 10:37

Edited by kimbow on Sunday 3rd March 10:38

[Hair Flick]

kimbow said:

Yes its a bit of a conundrum !! The slip on does sound nice but wont give the performance gains of the full Evolution system. However the trade off is no messing with the slip on, fit n go. The full system does need ECU map change or delete r module (£300 !!)to stop the cel light coming on and for a slight low rpm torque dip,(according to Evolve) due to the faster gas flow, as the primary cats are deleted ! The exhaust supplier should have told you this as you would have had problems if you thought the Evolution system was plug n go ! Anyway, a grand saved to spend on something else for the car !

Edited by kimbow on Sunday 3rd March 10:37

Edited by kimbow on Sunday 3rd March 10:38

I find it fascinating that any one would willingly sell at catless exhaust to a road user, forcing that road user to then find a "friendly" MOT station and for the sake of peanuts in power. The e92 is what? 414bhp, but how often do they ever get to explore that on the road. And a dealer that doesnt know about or mention about the issues, walk away.

[kimbow]

Fascinating indeed ! I explore the power on track mainly, I live quite near Snetterton and do trips to the 'ring and spa when I can. When my car was supercharged (very fascinating indeed !) it needed the akro exhaust. Strangely I also had no issues with mot either. I agree the seller of the exhaust to our friend on here should have mentioned the potential issues with the full exhaust. Petrol heads one and all, this is why were on this site, yes !

[Hair Flick]

totes amazin fascinating Whats snet like, looking at popping over some time this year

[cs1874]

TBH, I'm not too concerned if I don't get any reported power gains...414bhp is ample for getting into mischief...for me the look of the carbon tips, and the sound is more important...personally, I feel that the sound is a huge part of the v8 driving experience and the OEM exhaust is just too refined/restrained. I've done the mod within the box, but ideally I'd like a "proper" exhaust rather than a modded rear box.

I've been quoted
Slip On system (including Carbon tail pipes) - £2,299.90 + VAT

Evolution System (including Carbon tail pipes) - £3,819.90 + VAT

Just looking at the numbers and it's a no-brainer for me....Slip On.

[Hair Flick]

nearly 2500 for some slip ons? Get yourself down to AAS in Newcastle I am sure they would do the same but for much much less!

[griff7]

I had the remus slip on back boxes on mine and they sounded amazing far better than the akrapovic system as many people commented at the ring.The problem i had was spa last year and noise regs, i had to take the remus off and borrow a standard rear box which was a pain.To buy another decent slip on system was over 1k so i have a brand new akrapovic system with the delete system and carbon tips ready to fit in the garage as it will easily pass noise and is lighter and gives more power and i'm never selling the car so as a long term proposition it made sense for me.If it's about just making the car sound better then most of the slip on systems sound great.

Andy

[kimbow]

Hair Flick said:

totes amazin fascinating Whats snet like, looking at popping over some time this year

Snetterton is a great track, especially with the new bit of circuit theyve got now ! You will love it, some good fast straights and sweeping bends ('bombhole' especially )I love it and its a great drive once you get the hang of it.