Sodium Exhaust Valves

[chris68]

The valves on my 2.0 litre motor need replacement due to stem wear. The 38mm exhaust valves were originally sodium filled (for improved heat transfer) but the only source appears to be Porsche and they're more than a bit pricey .

I've read various pros and cons of sodium filled valves and wondered what people here had used, or if anyone had found a good aftermarket source??

Thanks,
Chris