3B Downpipe modification

[gmac78]

Hi Guys,

Since the head is off my S2, now is the prime time to fit a larger downpipe.

I have managed to source an RS2 downpipe but wondering now should i just modify the 3B one and save myself some money??...

Now then, for ease of fitment whats your thoughts on just cutting off the 2.5" pipework and welding on 3", retaining the upper section that bolts to the turbo and has wastegate pipework attached.

I have read that people think the upper section is restrictive and to just start a fresh and make a full new downpipe, this would be best i guess but more work etc and hoping to keep downtime to a minimum.

Realistically, would you notice the difference between a full 3" downpipe and a modified 3B one with 3" pipework attached just after the wastegate outlet?

Look forward to your replies.

Cheers
Gordon

[newsh]

The restriction is just after the turbo, where the gases are hottest. Fit the RS2 DP or make a 3" one.

[gmac78]

I could be wrong but i'm sure i read that the first part of the downpipe is the same part number for 3B/ABY/ADU. If this is correct, there would be no benefit to buying an RS2 DP then cutting the 2.75 off, replacing with 3". May as well just chop the 3B DP and modify accordingly.

[newsh]

You can re-use the flange

[mac2226]

I could be wrong but i'm sure i read that the first part of the downpipe is the same part number for 3B/ABY/ADU. If this is correct, there would be no benefit to buying an RS2 DP then cutting the 2.75 off, replacing with 3". May as well just chop the 3B DP and modify accordingly.

I just chop my Aby dp upto cast bit and build my mandrel 3" from there I did it this way on a rs2 hybrid setup worked ok for me

[gmac78]

I had a closer inspection of the downpipe today and yes the indentations do intrude some what into the gas flow, due to the curved shape of the indentations i'm just not sure how much they would affect the flow of gases and cause a restriction. For those who have gone the whole hog and fabricated a DP from turbo outlet onwards, what is access to the awkward bolt like? Better or worse than the standard DP?

[K Simmonds]

The downpipe fitted to my 3B is much, much easier to remove than the stock item, it's a full three inches from the turbo back.