I've had my 2.5 Boxster at an indicated 140mph and see no signs of float or instability. If anything, it was the most stable road car I've tried at that speed. (Others were Jaguar XK8, Porsche 996, 911 and BMW M5.)
I also run my 2.5 tiptronic to 147mph without a floating feel, could it be due to tyre pression or weak suspension?
the other thing that I have heard is that the 2.5 or 3.2 litre engine are apparently the same unit with different bore/stroke, if you rework a 2.5 and change chamber/piston etc..to 3.2 parts would this work out cheaper than buying a full motor?
anyone with an idea on this?