Very true regarding using the speed but it does have the additional flexability as you say. I do like the exclusivity of it as I said and it turns heads too, as not many people know what the hell it is. A guy at my work said to me when I got it, nice motor 2.5l ? I said 6l... he didn't believe me, so I dragged him out to the carpark at which point he just said "Holy @*!#"
Fuel wise I'm not too far off (3-4mpg difference) where I was with 350, but I do drive the Ro more slowly most days.
I was looking at some of the stuff you can get from Aus, but I'm quite happy with stock just now... maybe an exhaust at somepoint but I simply can't justify £1800 for the Wortec although the end pipes are huge... but I'd be looking elsewhere for a cheaper alternative I think, suggestions welcome