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Discussion Starter #1 (Edited)
Finally got round to finishing my little weekend project!

Basically, I got 2 old V8 back boxes off Ebay, gave them a lobotomy, cut out all the baffles and metal work.

Welded in 2 perforated pipes, with the main pipe having a valve on the exit. The 2nd pipe has a small helmholtz res pipe and a couple of angled baffle plates for quiet mode. The valves are remote control, with open/closed/then increments of 4 stages of closed/open.

Perforated pipes are wrapped in stainless wool, then continuous strand e-glass packed in the voids. The e-glass looked like a big Father Christmas beard! :)

I fitted them last night and was surprised how quiet they were!! I did a too good of a job!! It's quieter than standard before I fitted the X pipe!

I'm not keen on how quiet it is as I wanted louder and quiet switchable with the valves. I'll have to give it a bit more time to bed in.

DSG farts are less crackly and more burpy, like burrrrrpp. So my aim was to create a shouty exhaust that could be sedated with the valves, but the howly parp which I liked on the std exhaust is gone and with the new custom exhaust it is a deeper tone, especially at low revs that turns into a quiet deep sporty tight tone at higher revs. I can hear the supercharger whine more now, but probably because of the quieter exhaust.

So I'll have to give it a while to see if I do like it or the tone changes with some miles. They do say an exhaust is at it's quietest when new. Was thinking about removing the front little silencer as Smokey Joe said they make quite a difference. If I knew it was going to be this quiet, I would have put a solid pipe in, instead of the perforated pipe on the valved exit.

A big plus point is it definitely feels faster!! It feels like it would pull to 10,000rpm! :)

Just needs a few tweaks on tail pipe alignment. The right side is perfect, but the left is a little low.

Please don't judge the amateur welding, I'm a novice and I think the metal mix of aluminium/mild steel for the casing didn't help. :)

Once it's all fettled and aligned properly, and bed in, I will try and get some sound/video clips.

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Amazing work Dave. I can't believe it's gone quieter though lol.
As you say give it some mileage and it could well burn off some of that wool and make some more noise.
How much difference does opening and closing the valves make?
And I assume you took it for a little drive without the silencers on? ?
 

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Discussion Starter #3
I know, I really didn't expect it to be that quiet. I was expecting that I may have to add a silencer in. It has just the 2 little front silencers on the downpipes, then the back boxes!
To be honest I thought I might drive with the valves closed, but so far I'm driving with them open.

The valves basically remove the low down hum. They are a bit like a bass boost button!! With the closed, the sound it's just what I wanted for when I have people in the car and cruising, nice and quiet. Then an open valve gives loud fun, but it's not loud enough. The performance enhancement was surprising though!

I'm sure the DSG is changing gear quick and harder too!? :)

I didn't go for a drive as it was on axle stands so a bit of pain to get it back on the ground just for a bit of fun round the block.

Another option is to get 2 more valves and do a cut out, that should get the volume up!

If I didn't have the valves, I could have possibly put a sleeve inside the perforated tube to prevent the sound absorption. The only option I have now, is cut it all open, which I really don't want to do, again, replace the perforated tube on the valved side, or try removing the downpipe silencers.

So did it make a big difference on yours removing the downpipe silencers? Did you get chance to look inside to see if it's just a straight through silencer? I'd expect them given the size that they would be a straight through.
 

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So did it make a big difference on yours removing the downpipe silencers? Did you get chance to look inside to see if it's just a straight through silencer? I'd expect them given the size that they would be a straight through.
Yes it did and surprisingly so considering how small they are.
Yeah I still have them they are straight through with perforated pipe.
It sounds almost asbo ish at low revs if I mash the throttle so I tend to ease it in gently, and really nice from mid-range up.
 

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Discussion Starter #6
Going to cut them out at weekend and make some alignment adjustments.

Hope I can get the downpipes off! With exhausts, the closer you get to the front, the more stubborn the nuts and bolts!

Also noticed, the 3 studs are pressed in from underneath with the nut on top!? Hope I can get to them!

Will try and get some vids.
 

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I left mine with my local garage to do, he said they were a pain to get off.
I think a crows foot is required to get at the nuts.
 

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Discussion Starter #8
Yeah, was thinking that, as I think it would be difficult from the top through the engine! I'll have to assess how much of a PITA they are! :) Why Audi put the nuts on top, I'll never know!
 

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Ask DAP on YouTube has a few good videos on the b8.5 s4 so most of it is the same. He definitely does downpipes I've seen it. Worth a watch.
 
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