OK... i've used 2 solutions...
1.... Use the siamesed headers from a monoshock SRX... they look good although they curve a bit one way (to pass to one side of the oil tank/cooler unit on the monoshock.)
2. ... get a set made up... this can be expensive, but there are plenty of good pipe makers about... you'll find the ones I had made up on a pic of my #1 srx somewhere in the gallery. the whole lot, silencer and down pipes cost me £160.... but I think Nick realised it was cheap as he charged my Son £300 for a similar setup on his Morini Sport.