I'm sure people won't mind you making a quick comparison.
I would have thought the ST, especially in your spec will be much quicker than a Zed. I followed an Orange ST down a slip road and onto a motorway in my 650i, and although I stuck with him up to silly speeds, I was well impressed just how quick it was. He had 4 in the car too. Obviously he was trying to impress his mates by trying to leave me for dead, so I had to oblige by sticking to his bumper...
See i had a play in the zed and a mates ST and did some nice rolling sprints etc and the 350 had the edge but quite a bit. However i did notice - when in the car with my friend - that he isnt very good at changing gears and changes way too early, which could be why the zed had the advantage