PT best vibration padding technique

I’ve just got a new CPU (it has new printing '2.4 wired' now ), a new shark receiver and coded HR strap to solve my vibration and no HR issues under warranty. The returns policy of Saris is amazing btw - they send straight away without asking for the old unit back!

I still appear to be having a problem with vibration however . Holding + 250 watts steady at 90 rpm is impossible without the dreaded ‘---‘. I've mounted the shark fin upside down on the chainstay as per recommendations here but I was wondering if anyone can recommend padding that works well also?

Because I'm very tall and my frame is small in comparison (it's still the largest) I'm wondering if its maybe flex related because my seat it so high, so I want to try more vibration dampening before I return the hub.

I used the foam that the power tap cpu came in. I had drops till i used the sponge foam.