Just like some clarification on this issue. My friend tells me that anything can be legal as long as you have an engineering certificate authorising it and of course you have to register this with the RTA or whatever in your state. I was under the impression that they have limits with stuff like this. For example, my friend says that hydraulic shocks are legal as long as you have an engineering certificate supporting it, but I was under the impression you are not allowed to have them legally on street vehicles.