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Keethos

Keethos' GT86 Journey Back To Health + Mods

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There are various people with decatted manifolds who aren't having volume issues because of the rest of the exhaust system that they are using and I admit, it was a gamble for me as the Cobra is quite loud any ways but its all part of the journey. Even with the increase in volume, the noise it makes now, especially when you are flat out and even more so when you lift off sounds epic, its just the low down sound under load that is too much for me (especially when cruising on the motorway) and for track use. Not only that but the increase in torque at mid range is definitely worth the hassle.

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Not all manifolds are equal in terms of volume. They can't really be categorised as catted and non catted. The tuning developments and the similarly designed FA20 Club manifolds are aggressive. Keith after seeing that video your car is very harsh on overrun, you need a resonator in there somewhere :lol:

 

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1 hour ago, Rich said:

My Milltek non-res was only 97dB with decat manifold (though I retained the stock front pipe). I think the cobra is pretty loud!

Keith's non-res got 108db a few years ago!

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So update, last Friday, I visited John Ashley Exhausts in Walsall to see what they could do in terms of quietening down the car.  I was hoping they could modify the Berk HFC since it probably won't do much for me but sadly they said there really wasn't much room there to play with and most of the noise is due to the design and size of the back box.  Not only that, but the resonated pipe itself could have been bigger, so that is what we did, we chopped out the resonated section of the mid pipe and welded in a slightly shorter but offset oval shaped silencer since there was a fair amount of space through the tunnel underneath the prop-shaft which ultimately meant more volume to dampen the sound down by.

Good news, it work, it lowered the volume of the car considerably....bad news....maybe a lil too quiet :P I think it is currently slightly quieter than it was before the manifold which means I shouldn't have any issues now getting on track (will double check at the Midland meet in a couple of weeks hopefully)....then again I might have gone partially deaf so only the sound meter will tell :D  But to be fair, it was similar to how I was when I went from non-res to resonated, I was saddened by the drop in noise, but when I went resonated, I eventually grew to love the sound that the car made then so I'm sure can get on with the sound/volume of it now.  But it is a shame especially since it sounded so good, the pops and crackles (though it does still pop slightly but you can't always hear it), the loud barks when you blipped the throttle and most of all, the lift off from high revs....sounded soooo good.

Now you tend to hear the engine and the manifold more than the exhaust itself which leads me to my main issue, the little sound the exhaust does actually make for some reason now rattles more, very raspy like which I'm not a fan of at all.  This I don't really want to get used to so I may look into getting a new Cat back system at some point, I might even go back to John Ashley to see if they'd make a custom one to give better flow (they recommend Y pipes at the back with individual silencers rather than a big back box) while having it sound exactly how I'd like it to.

Another part of me is a little disappointed that it's managed to quieten the car down so much as my back up plan was to turbo the car to help reduce the noise level....now I don't "need" to turbo it anymore :lol:

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Do you know what kind of silencer they fitted? Offset sounds like it might be a chamber type silencer. Good for reducing sound but can lack high frequency attenuation giving the rasp. Just a thought.

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I've got a valved system on my Mini @Keethos and it sounds like something your after! - A remote control opens a valve that bypasses the silencers so it's just a straight pipe for hooning purposes!:lol: It can be closed off and directed through silencers again at the push of a button! - Not sure how much an exhaust place would charge to fit though! :)

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23 minutes ago, Tom B said:

Yeah that's one Jeff! You get the best of both worlds! Chuffed with mine. B)

It does looks good. The chap that bought my stock cat back was planning to do something similar. 

Sound like its really loud when bypassing though!

 

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On 07/02/2017 at 8:49 PM, Ade said:

Do you know what kind of silencer they fitted? Offset sounds like it might be a chamber type silencer. Good for reducing sound but can lack high frequency attenuation giving the rasp. Just a thought.

Sorry for the late response don't know what it's called but it was a perforated tube through an oval chamber stuffed with a load of grey fibre wadding stuffed in it.

And Tom that does sound interesting, do like my gadgets, but would need to hear the sound more importantly.

Sadly though some bad news, after a couple of days, the volume of the car has suddenly shot up.  Not as loud as it was but noticeable but it does sound a bit weird now, sounds a bit clanky yet more Subaru burble like if that makes sense.  Either it's blown all the wadding out or it's split somewhere, either way, will be going back to them to get it replaced and while it's there, just get a whole new catback instead, saves faffing around with repairing and mixing and matching, hopefully they can create something that meets my exact needs.  Got it booked in next Thursday so the true test will be the very next day at Oulton Park.

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An update from my post:

As I mentioned previously, a couple of days after having a John Ashley custom silencer installed, the volume went from really quiet to really loud again (not as loud as it was before the silencer) and I was worried that either there was a weld issue or maybe the wadding inside the silencer had been burnt out.  Not only that but the rattling/raspy sound was worse than ever.

So about a week later, I booked my car in again to see what the issue is while changing the back box completely from a Cobra system to a custom made Y shape system which would hopefully improve flow and hopefully remove any raspiness.  Found out that the silencer was perfectly fine, what had happened was one of the bolts holding the mid pipe to the back box had fallen out and the exhaust was blowing the gasket out so I kept the silencer as is.

After several hours of work, the lads at John Ashley Exhausts finished my custom Y shape back box so now I'm essentially running a custom John Ashley catback exhaust system and I've got to say, the volume is about spot on.  It's louder than when the silencer was fitted and still quieter than it was before....even had a sound meter to test it while I was there and was getting about 88dbs but the proof of the pudding was on track a couple of Fridays ago at Oulton Park where as you can hear from the video, I only got 83dbs....then again I was only doing 5000rpm rather than the usual 5500rpm but there or there abouts anyways so very happy with the result.  Even managed to re-use the black outverted tips which I like.

The only slight gripe at the moment is the original gripe of that raspy sound, the car, when cold, would sound a bit raspy/rattly around 4000rpm part load but once it's hot, it doesn't rasp or rattle as much or at all sometimes so I'm just hoping that once they get carboned up that they'll reduce or even stop completely but again, still pretty happy with how they've turned out!

So now I'm running the Tuning Developments Unequal Length Decat Manifold with their Overpipe, Berk High Flow Cat followed by John Ashley's Custom Silenced Y Shape Catback Exhaust System with Cobra's Black Outverted Exhaust Tips

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7 minutes ago, Keethos said:

Yeah, not a fan of the thin looking slash cuts, much prefer something a lil thicker 😉

 

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I'm a fan of the titanium rolled tips myself. :D

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46 minutes ago, Paul said:

I'm a fan of the titanium rolled tips myself. :D

Just roller for me.

 

@Keethos glad you like the setup. Sounds pretty good. I love Oulton park, must have been fun in the wet!

 

 

 

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It was a very good day, but I think I was quite cautious around some of the corners because of the wet, especially the Island Bend, I always seem to brake very early even though its so flat, think I've still got some of that fear from crashing in me since you're facing a barrier for the return to Britten's after the Shell Oils Corner hairpin.

 

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Having just read this after @GT86-Ian told me that your car is Renault liquid yellow not 86 yellow because of the track incident. What a story of recovery and stress, most would of sold up at that point. How come not all the pictures load though. I've still not seen any with the 57 getters on show ready? 

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