Hi Harry,
Have you tried speaking to Hayward and Scott? They are probably your best bet for bespoke exhaust work. Having just bought an Aero S1, I may be interested in your side exit system but I'm assuming that it's from your S2 and therefore won't fit?
Strangely, the car I bought was advertised as having a Sports Exhaust but having now driven it a bit, it seems far too quite and I'm convincing myself that it is just standard. It has single oval tail pipes.
