Cybernations was the first company to start making turbos for the RSX and are known across the continent for their turbos. The HKS kit as far as I know puts down smaller numbers, but at a much higher price.

As for engine management for the HKS kit I think it would use the V-Con Pro (sp? I always forget the name) and they showed the kit off on a 2005 RSX at SEMA. As for Cybernations kit, i'm not really sure.