Technically yes, i know it doesn' seem right but it is true. All modifications to suspension and brakes that involve non std/manufacturers parts (ie leyland/bmc) need to be certified by an engineer. There are alot of people that have them on the car and not had them certified though, just makes things iffy with insurance. Find and engineer and speak to them about it before committing funds to it. Show them the units(ie pics and specs) and see if he/she sees a problem. We know that there won't be but it is up to the individual engineer. You can also get a costing. To be honest it should cost bugger all for that type of thing. If there is other stuff speak to them on all matters and get them to do all mods at one.
On another note, technically those clear lenses that all the wrx's and the like have on there car are supposes to be engineered too. That's why the cops can defect them at any time... Thats gottta suck
Cheers
Aaron