F8x crappy exhaust note and how to improve

[Bob MG]

ok so Ive installed a full Akra Evo system to my M4 and also fitted the AR catless downpipes and its obnoxiously loud.

Ive since taken off the DP's and the Akra on its own is now too soft and I want a bit more. Im thinking hi flow catted downpipes may be the answer, BUT...even with the OEM system, you get that farty sound when you jump off the accelerator when driving hard and its sounds worse with the Akra and totally embarrassing with the Cat-less downpipes added to the mix.

Im thinking that the issue is caused when the valve flaps open and was wondering if we could just close them and run the system like that? The Awron gauge has a feature to close the flaps permanently or open when desired but Im wondering if this will create the fix Im looking for without sacrificing hp? I wouldn't think it would rob HP since the silencer isn't restrictive and shouldn't restrict airflow to the point of robbing hp.

The Akra + ER set up sounded unbelievable at idle and low revs, and just fucked up loud when the valves opened after 4k. When the valves are kept closed it sounds great and also illuminates that ridiculous fart sound (which is amplified like african thunder cracks with the ER DP's)

All thoughts and comments eagerly awaited as this is driving me nuts as Ive got my ER DP's sitting wrapped in plastic on my garage floor

[LukasAT]

please go to an ENT doctor .. there is obviously something wrong with your ears!

[NorCal f80]

I can't wait to get my shit-sounding OEM exhaust off.

[hellrotm]

The exhaust on this car is tough. I have yet to hear anything that really improves the exhaust note, instead of just making the crappy note louder. The only exhaust that shows promise is the Active Autowerke. It actually gives the exhaust a deeper tone, which this car desperately needs.

[Sal@AUTOcouture]

Bob I went thru the same thing. I think the perfect solution is to run the catless downpipes, OEM midpipe, and aftermarket rear.

[NorCal f80]

Easiest and cheapest solution, although it's not 100% perfect but it is 100% better than stock: http://f80.bimmerpost.com/forums/sho....php?t=1045821

[Black Gold]

I can tell you that downpipes with HFC will clean up the sound for sure compared to a catless downpipe setup. the cats will act like another resonator and eliminate that rasp and unclean sound.

I think it may be worth a try, but you can also try to disable the valves and keep it open to make your current akra sound better at low RPM without the downpipes. that's a free mod, and worth a try to see if you like it.

on the OEM car, disabling the valves makes a WORLD of difference at idle and low RPM. so the same could be true for your current setup (sans downpipes). that's what I would do, then go from there

[Bob MG]

Originally Posted by KennyPowers

I can tell you that downpipes with HFC will clean up the sound for sure compared to a catless downpipe setup. the cats will act like another resonator and eliminate that rasp and unclean sound.

I think it may be worth a try, but you can also try to disable the valves and keep it open to make your current akra sound better at low RPM without the downpipes. that's a free mod, and worth a try to see if you like it.

on the OEM car, disabling the valves makes a WORLD of difference at idle and low RPM. so the same could be true for your current setup (sans downpipes). that's what I would do, then go from there

Thanks bro I'm agreeing with what you have said. Reckon the AFE hi flow catted downpipes will make the world of difference and get me the middle of the road sound with extra performance I was originally after with replacing the down pipes.

Will leave the valve as is for now and just wait for the new DP's to arrive.

I do however think the Aaron gauge set up is genius as it allows you to control the valve and you can opt to have it open / closed or flexible as per OEM. I had this in my Ferrari CS and it is great

Plus it also gives a fix for the DP's which will probably be an issue even with a high flow 200cpi catted down pipes

[CanAutM3]

Originally Posted by Bob MG

ok so Ive installed a full Akra Evo system to my M4 and also fitted the AR catless downpipes and its obnoxiously loud.

Ive since taken off the DP's and the Akra on its own is now too soft and I want a bit more. Im thinking hi flow catted downpipes may be the answer, BUT...even with the OEM system, you get that farty sound when you jump off the accelerator when driving hard and its sounds worse with the Akra and totally embarrassing with the Cat-less downpipes added to the mix.

Im thinking that the issue is caused when the valve flaps open and was wondering if we could just close them and run the system like that? The Awron gauge has a feature to close the flaps permanently or open when desired but Im wondering if this will create the fix Im looking for without sacrificing hp? I wouldn't think it would rob HP since the silencer isn't restrictive and shouldn't restrict airflow to the point of robbing hp.

The Akra + ER set up sounded unbelievable at idle and low revs, and just fucked up loud when the valves opened after 4k. When the valves are kept closed it sounds great and also illuminates that ridiculous fart sound (which is amplified like african thunder cracks with the ER DP's)

All thoughts and comments eagerly awaited as this is driving me nuts as Ive got my ER DP's sitting wrapped in plastic on my garage floor

IMO the farts come from the anti-lag feature, no exhaust system will get rid of them. The louder the system, the louder the farts ,

[Bob MG]

Well ER mailed me and:

We will be making a high flow metallic catted version in January.

The high flow metallic catted version will be just slightly louder than the factory downpipe an considerably quieter than our catless downpipes. I think this would be the ideal sound for you if you are looking for it to just be a little bid louder than factory

[WhiteFlashE90]

Originally Posted by BlackJetE90

The exhaust on this car is tough. I have yet to hear anything that really improves the exhaust note, instead of just making the crappy note louder. The only exhaust that shows promise is the Active Autowerke. It actually gives the exhaust a deeper tone, which this car desperately needs.

Agree

[Wes Howell]

OP - Are you saying you have 2 different sets of carless DPs? AR installed and new set of ER? If so, why? Do you expect them to sound any different? Aren't they both carless DP's? A bit confused.

LMK if you sell a set as I want to try something a bit louder.

Thanks!
Wes

[Bob MG]

Originally Posted by Wes Howell

OP - Are you saying you have 2 different sets of carless DPs? AR installed and new set of ER? If so, why? Do you expect them to sound any different? Aren't they both carless DP's? A bit confused.

LMK if you sell a set as I want to try something a bit louder.

Thanks!
Wes

I have the ER catless and waiting for either AFE or ER hi flow cat downpipes as the catless are too loud with the Akra set up.

Will sell the catless set

[w00tw00t]

record a S65 V8, install a really loud speaker in the trunk pointing out back, sync the sounds with your throttle pedal and baam! everyone around you will think you have a V8

[Bob MG]

Check this out..

I reckon the ER downpipes will have 200 cpi which should have good flow and remove some of the unwanted loudness

[Wes Howell]

Originally Posted by Bob MG

I have the ER catless and waiting for either AFE or ER hi flow cat downpipes as the catless are too loud with the Akra set up.

Will sell the catless set

Thanks Bob - Feel free to ping me when your set is available.