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Hi,

I have got my car booked in for some custom downpipes next week and wondered if anyone has any experience of what I can expect performancewise.

The down pipe will be an all stainless steel construction and fully back purged TIG welded. The down pipes will be 3" diameter with Magnaflow 100 cell metal race cats and obviously no pre cats.

I am also getting the centre section changed to 3" pipe with V clamp fittings but keeping the standard rear box partly for OEM looks, low noise and low cost. If this proves to be a restriction it can also be changed in the future.

Hopefully the above will be a decent improvement and fully fitted will be a good bit cheaper then just miltek downpipes would be without fitting.

My only slight concern was that i might lose some low down torque due to higher diameter down pipes but I have been told this will not be the case and if anything it should improve due to the turbo spooling up about 500rpm earlier.

Howerver when I have changed the manifold on a turbo car before which was larger diameter I did loose quite a lot of torque and slower turbo spool up but I think that is because the larger diameter pipes before the turbo mean the exhaust gasses travel more slowly through the turbo. So hopefully that will not be the case with larger diameter pipes after the turbo.

I will be adding some picture of the installation in due course and let you know my findings.

In the mean time anythoughts would be welcome as its not to late to change the spec yet!

good mod mate . this is exactly what im after, can i ask who is doing the fabrication because id be up for a set without the cats.jim

Jimbo.. I'd go to Pipewerx. It's not far from the Wiggin Tree near Parbold. The guys name is Ian and he done a great job on my S4, and he was pretty cheap too.

Assuming this is for the RS??

im actually after some 3"downpipes to fit the honda

and water/meth injection

Definately go to Pipewerx Jimbo, the systems are top notch. A customer reported an 18bhp increase with just a Pipewerx downpipe on an S3, Ian may even give you a run around the block in his 700bhp twin engined caddy van he's built or a 400bhp lotus elise.

v interesting. cheers all

I think it's the old story that these custom exhaust mods are quite doable and economic but you really need to have a remap to take advantage of the mods.

Unfortunately we don't have an MRC down here in Oz. Though with this sort of exhaust mod and the remap I'd imagine MRC would be getting around 440 to 450 hp and alot more torque. I think with the full Milltek system it is 460 hp and an even greater % increase in peak torque.

Anyway, look forward to seeing the results and perhaps a dyno chart. I think stock the RS4 is putting down around 220 kw to the wheels.

3" custom pipes will be a bastrd to fit in situ, there is very little clearance past the gearbox to be honest I cant see how it is possible and leave enough space so as not to roast something/tunnel/etc in my view 63mm is plenty unless you are building for RS6s and 650hp plus.
You should consider putting the flexis higher up as they will get scraped if placed where the original ones are. I retained the gutted Pre-cats, saves allot of work / easier to get the angle right / front o2 bosses stay etc.

Consider V-band clamps on the dps as engine work, gearbox work etc is much easier,

see my 246 album on the last pages.

the dps and cats will make the cabin quite a bit louder especially 3" and on motorways etc.

Try and get the runs under the car as high up as possible, jack up whilst welding and dont forget to alow for expansion when hot.

good luck with the DPs these are mine (63mm) 100 cel cats.

Hi, I have been trying to add some photos of my custom down pipes which are under construction but cant seem to get the attachment to add. Can anyone give me some advice! I sure I am missing something obvious but when i browse for the image and select it it wontr let me attach it. thanks

Probably have to upload to an image hosting website first, such as Photobucket, then insert the IMG file path into the message on here...

Lilke this? fingers crossed!

http://s499.photobucket.com/albums/rr36 ... jenks2.jpg

http://s499.photobucket.com/albums/rr36 ... jenks1.jpg

No like this.

Which will give you this effect.

like this?