Don't suppose anyone knows if the 99 R1 engine has the same exhaust port layout as the 06 5VY engine. Any idea if a manifold from a 99 would fit an 06 (in the head area at least)?

Cheers

I very much doubt it, the block / cylinder on an 04 onwards engine is far more canted over than the earlier engines so even if the ports are the same size, the manifold would sit at the wrong angle to exit the car correctly if bolted to the later engine

It won't fit! The port size is the same and the spacing isn't far off. But, as Chris said, the later engine is canted forward a fair bit more. I'm just going from a 5JJ to a 5VY so I know only too well

There may be a chance that you could cut and shut the earlier manifold though - depends on your fabricating skills I guess?

Wyn