Hi all,

I am thinking of renewing the actual dual pipes (B20) that join to the steel flange that bolts onto the bottom of the manifold. The old pipes are fairly rusty, although no holes yet. New ones are expensive, and I can sand bend new pipe easily enough, so I thought I'd give it a try.

Does anyone know whether the pipes are butt-welded to the plate, or go all the way through the flange and are located by the weld? When I look down into the pipe, I can't see any sign of a join. Does this mean that the pipes come through the plate all they way to the gasket surface?

Am I safe to just grind the plate flat and butt-weld new pipes to it? Should I use bigger diameter pipe, or stick with the original size? What about length to the collector? I notice on my B23 that the dual pipes go a lot further (maybe a foot or so) before they meet in the collector. That sounds like there might be torque gains in lengthening the pipes.

Any advice welcome, as always.

Regards
JohnH