I've fitted a 3.0L Alfa 12v to my Haynes Roadster and am currently look at the exhausts.

The question I have is what diameter does the balance pipe need to be? I'm planning on using a 38mm internal primaries and 58mm exhaust system.

Knowing the size will help with routing around the sump to linking the systems.

Regards Dan.

I used a 45mm dia link pipe and it made the exhausts a bit quieter but seemed to have no effect on power.

I use 25mm on my Mazda V6 conversions - the stock Mx6 exhaust has a very small link pipe , maybe 20mm , but its only about 25mm long !

Ok, changing tack completely, what purpose do they serve? Is it needed?

Regards Dan.

Serves no purpose on a 6 cylinder except to improve the sound, without when you stand to one side of the car you hear 3 cylinders instead of 6.

Hmmm, the Alfa was partially chosen for it's noise.

Best I find a way to preserve it then.

Regards Dan.