Hi I own v9 sti and the car starts to bounce quite a lot on the motorway (70mph). I had a friend of mine in the car and it made him feel quite sick and this guy has owned a fews performance cars. I check the tyres pressures quite regularly. There is no noise coming from the suspension.

 

You need to better describe what it is doing.
But if you are talking about a constant 'patter' where the front and back seem to patter out of synch with each other. Then that would be quite normal for a mono tube suspension, and I believe mono tube are standard on Newage STi's (???)

You could check the movement of each corner by bouncing on it, and seeing how it reacts, as sticking shocks, especially rear ones are quite common on V8's. Perhaps V9's too?