For more info on the predator go here :
http://www.the-pred.co.uk/
as for the rockers the latest ones to come out were the blue skeleton type.
the one I have are the silver machined on one side type.
the original have holes in them.
your choice really none of them are bad.
there was once a list that compared the xrs to the X10 as to what came standared on the X10 but was an option for the xrs, but I can't remember where it was.sorry. Basically every thing made of plastic on the xrs was alloy on the X10, the oneway on the shaft, and the towers were carbon.
A worth while mod for both cars was the 40 percent lighter chassis.
hope this helps.