I'll put my vote in for Harrison(
www.cobrakits.com.au).
Built one with my brother a few years back, he now compaigns it heavily on the track and seems to have had some success.
CR's are very popular down south(especially on this forum) and a good choice also. Interesting we don't really see them up here in QLD. I only know of one up here.
If you feel like a holiday up in QLD(Gold Coast). You will see more Cobra stuff here than anywhere else in Oz. We have Harrison(manufacturer), Snake Bite(Cobra accessories) and DRB all pretty close to each other.
And 1st Sunday of month we have QLD Club Meet at Sanctuary Cove(Gold Coast). Probably get 30 odd Cobra's and a few GT40's on a regular basis.
I reckon it would be worth the trip, just to meet Warrick Harrison himself. Warrick(and his partner) is the most active Cobra manufacturer in the Club.