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Discussion Starter #1
I am looking for a new cat back exhaust to replace OEM on my selespeed.

I'm aware of the current branded options (wizard, supersprint, ragazzon, scorpion etc) however I want to keep the sound as OEM as possible.....maybe with slightly more growl. The car needs to be quiet enough at 2.3-3k revs so it can sit on a motorway and be comfortable to a 40 year old!

Anyone have any experience with some of the custom build jobs or recommend a good place within reach of Yorkshire?
 

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"custom build" usually means selecting an off-the-shelf stainless steel silencer based on size and level of packing, rather than actually scientifically building a silencer of the correct volume/chambers to do what you want.. It usually gives deep, bassy tones, a little drone at 2,000 - 2,500rpm. GTAs need resonators to get the most out of that lovely engine. Cut open a standard exhaust and you will see exactly how Alfa did it and why they didn't just go straight-through.

I would stick with OEM in your circumstances, but get a good welder to cut out the middle silencer and tube it, and maybe (if that isn't enough) open up the original backbox and tweak it for flow. I did this on my old '55 plate Bianco Nuvola 147 GTA and it sounded fantastic under load and barely any different when driving steadily.
 

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"custom build" usually means selecting an off-the-shelf stainless steel silencer based on size and level of packing, rather than actually scientifically building a silencer of the correct volume/chambers to do what you want.. It usually gives deep, bassy tones, a little drone at 2,000 - 2,500rpm. GTAs need resonators to get the most out of that lovely engine. Cut open a standard exhaust and you will see exactly how Alfa did it and why they didn't just go straight-through.

I would stick with OEM in your circumstances, but get a good welder to cut out the middle silencer and tube it, and maybe (if that isn't enough) open up the original backbox and tweak it for flow. I did this on my old '55 plate Bianco Nuvola 147 GTA and it sounded fantastic under load and barely any different when driving steadily.
I thought it sounded quite fruity!
 

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I thought it sounded quite fruity!
I think I just did the backbox now that I recall, and the centre section is still got the mini silencer in it. You'd need to poke your head under for a look to doublecheck but that backbox has been free-flowed inside and a bit of a packing taken out :D
 

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I think I just did the backbox now that I recall, and the centre section is still got the mini silencer in it. You'd need to poke your head under for a look to doublecheck but that backbox has been free-flowed inside and a bit of a packing taken out :D
Sounds intriguing. Don't spose you could whip up a quick how-to Mr Pud? :teacher:
 

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I cut two squares out, a large one on the top of the silencer casing and a small one on the front, then took out some of the packing and I think there was a part of the pipe that tapered down which I cut off (that might be how a 156 GTA exhaust is as I've done both, hard to recall which is which).

Be aware, welding it back together was like trying to weld tin-foil, unless you have a welder with plenty of adjustment you will struggle to avoid blowing holes in it.
 

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I cut two squares out, a large one on the front of the silencer casing and a small one on the front, then took out some of the packing and I think there was a part of the pipe that tapered down which I cut off (that might be how a 156 GTA exhaust is as I've done both, hard to recall which is which).

Be aware, welding it back together was like trying to weld tin-foil, unless you have a welder with plenty of adjustment you will struggle to avoid blowing holes in it.
Sounds simple enough but no welding experience yet so probly too advanced for me for now. But if I can get a hold of an old back box from a wreckers I can dismember it to see what's inside and how it works for a start. And then try to weld it back together when I get a welder :thumbup:
 

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Sorry I just edited my original post, I cut the large hole on the top surface of the silencer. If you can get hold of an original backbox then you have nothing to lose by trying. Even if you have to get a professional to weld it back up for you.
 

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On a slightly different subject I just discovered these when looking for down pipes. Way cheaper than the Italian or Japanese ones but not equal length. Alfaholics are known for awesome Alfa upgrades so how important is equal length really? These guys say cleaning up the flow is way more important as the stock down pipes change diameter a few times

https://www.alfaholics.com/race-per...teel-sports-exhaust/front-pipes-–-147156-gta/
 

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On a slightly different subject I just discovered these when looking for down pipes. Way cheaper than the Italian or Japanese ones but not equal length. Alfaholics are known for awesome Alfa upgrades so how important is equal length really? These guys say cleaning up the flow is way more important as the stock down pipes change diameter a few times

https://www.alfaholics.com/race-per...teel-sports-exhaust/front-pipes-–-147156-gta/
These are pretty nice downpipes, I had them on my GTA. I only swapped them for some original Alfa Romeo downpipes because in combination with the decat manifolds & stainless cat-back system there was too much resonance from using stainless downpipes. Putting back in place the mild steel downpipes cured the issue.

Don't forget the advertised prices are excluding VAT, so add 20%.
 

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These are pretty nice downpipes, I had them on my GTA. I only swapped them for some original Alfa Romeo downpipes because in combination with the decat manifolds & stainless cat-back system there was too much resonance from using stainless downpipes. Putting back in place the mild steel downpipes cured the issue.

Don't forget the advertised prices are excluding VAT, so add 20%.
By resonance you mean exhaust drone?
 

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Discussion Starter #15
Got a quote from Tony Banks in Leeds today - £500 for a catback.

Apparently will give 15bhp improvement with no other mods!

Seems a bit pricy when a powerflow quote was £100 less.

I just want a new standard backbox - anyone got one for sale that they are happy to post/near enough to Yorkshire for a drive out?
 

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OEM backbox is showing as orderable, p/n 60676397 and list price of 392.92+VAT. But they are very nice for a factory system, if you get rid of your manifold cats and the middle silencer then the OEM backbox sounds lovely.

At Wizard Exhausts we've been talking about doing a OEM replica backboxes in stainless steel for years for all those who want as close to standard as possible, but we've just been too busy to do it.
 

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It sounds lovely anyway, its just difficult to hear inside the car.
 

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im 39 and could not live without my wizard, it has now fused with the car's dna. It's completely usable from the inside the cabin, all the way up to 153 mph, and there is no drone. My friends think it's to loud inside before sitting in the car, but when they do, they are suprised on how civilised it is inside the cabin.
 

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I am looking for a new cat back exhaust to replace OEM on my selespeed.

I'm aware of the current branded options (wizard, supersprint, ragazzon, scorpion etc) however I want to keep the sound as OEM as possible.....maybe with slightly more growl. The car needs to be quiet enough at 2.3-3k revs so it can sit on a motorway and be comfortable to a 40 year old!

Anyone have any experience with some of the custom build jobs or recommend a good place within reach of Yorkshire?
Ive got a CSC stainless cat back on mine and it sounds pretty similar to standard but just a little deeper on tickover and a bit louder at high revs but nice and quiet on the motorway

Mine is a 156 though so may sound different on a 147 maybe?
 

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At Wizard Exhausts we've been talking about doing a OEM replica backboxes in stainless steel for years for all those who want as close to standard as possible, but we've just been too busy to do it.
Please do this Dan. I promise I'll be your first customer. :yes:
If you can make them de-rasp the CF2 manifolds it would be a bonus - but not a deal-breaker. :thumbup:
 
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