Who really gives two shits?
By blabbering on about 'Proper RST' this and '1.6 CVH' that just shows you are living in the dark ages! Zetec turbo's are over 20mph faster top end than any 1600cc CVH, so why waste money ending up with a slower car using outdated engine tehnology just so some sad faecetious gets in the owners club can argue their free time away about who holds the record!
If you don't want to spend mega money or want to keep the car original but fast then fair enough, but if you want fast qtrs or top speed records and ultimate power then Zetec turbo is the only sensible way to go!