Another way around it would be to get a half bonnet with scoop ( left hand side as opposed to the orginal triumph engined Plus 4 right hand side job) made by someone like Malvern Sheet metal - would cosy you about £495 and apart from being a really pro way of doing it, it gives an excellent air source for the TB's

G

I have measured the air horns, they are 40mm (as described on the Jenvey page for Mazda 2.0 throttle body kit) and I phoned Jenvey to be sure. So I can use the internal itg filter.

A cheaper solution could be this one:
http://www.pipercross.net/competition/products_600_airbox.asp

But it looks as one would get warmer air only, because the bow departs the intake from the scoop - and with a filter fitted even more, therefore not getting the benefit of cold air, the scoop in the bonnet delivers.

Hi Cerealsurfer

thanks for your comment. In the meantime I have had a closer view to the pic of Don´s 4/4. It looks like the whole engine is leaner and the throttle bodies are more inside the bonnet. On the P4SS the standard Piper cross airfilter is already using part of the scoop. I guess I have bad luck neither with the Reverie nor with the Piper cross solution as both items are more extended than the bonnet allows.