wrist pins always come with the pistons.. or at least they should.
Wahl uses stock Mahle piston blanks, then cuts em to spec himself.
He might simply be able to get a loose set of Mahle pistons for a stock 3.2 carrera via Mahle.
But you'll have to be sure that our pistons are fully in spec... You might have to ship them over to him.
Wahl - Spezialkolben GmbH
Check with Peterfrans on the forum here, he's dealt with Wahl before , he needed some rs spec made...