Ok, sorry about the slow reply.
I found that the suspension made the car behave in a much more controlable way, I was able to predict what it was going to do, which was sometimes "oops" lol. Made the whole car much nicer to drive and by the end of the day I was pretty much able to link the whole track.
The locker helped also as when I flawed it on the flick back it would spin both wheels instead of just the one and therefore give again more control, sounds backwards I know, but when you have one wheel spinning and one gripping it really sucks, as you have to drag that tyre around with you.
Hope that helps, if not, please feel free to ask specific questions and I'll do my best to answer!
Dan.