It was VERY "unofficial" to be sure, and I had some issues with my GPS speed readings. I think my highest reliable speed was 154mph. But don't forget about Joshua Finn
@FAI-F1D! I think he holds the record between us two - I can't say for sure, but I think it was 175mph.
FWIW: We stuck to "mostly foamboard" for our challenge. We allowed carbon fiber tubes/rods for spars, and Finn used thin plywood on one of his wing-saddle attachments which we also thought was fine. I also used paint stir sticks on my belly as skids, and in a few places to reinforce a nose-repair.
But the flying surfaces, control surfaces, all the main construction was foamboard, hot glue and tape. We didn't get into sheeting or glassing at all, and in my opinion that would kinda defeat the purpose of a "foamboard speed plane". Once you sheet or glass, the foamboard is no longer the structural element, it's a substrate - which is exactly the proper way to use foam under glass - but then you no longer have a "foamboard plane", you have a "foam core glassed plane".