Considering the engine isn't even out yet in the US (june arrival on Horizon), it's hard to say if there is a replacement piston sleeve. The sleeve on the WC edition engines is slightly different, I'm sure of that. Just very mild port arrangement changes. I don't have much to compare, as I never had a Truhe edition, nor do I have a Discovery right now. Also, the P/S that we get from Adrien are always different, so for me it's like a box of chocolates. If I can discover anything profound, I will let you know. I see Horizon doesn't even have a 5 port sleeve for sale on the site. I'm surprised by that.