I found these:
Metric Studs - TE-CO
Metric Coupling (Extension) Nuts - TE-CO
they should work, but I don't know what the thread type/diameter is supposed to be. They have them on M6 x 1.0 .. M8 x 1.25 .. M10 x 1.5 .. M12 x 1.75 .. M16 x 2.0 .. M20 x 2.5 .. M24 x 3.0
Anyone knows which is the correct one?
Edit: looking at Stillen's website I think its a 24mm thread so it would be M24 x 3.0...right?