There was chatter at one point about the welds on CX racing stuff being a concern (particularly the exhaust turbo header).....so you will want to check the welds carefully prior to putting everything together. Front and rear strut tower braces, a roll bar, Apex front side structure supports, and maybe stiffen up the rails .......bad dog used to make thick steel rails that fit right over the originals and then have them welded on. 500 horsepower is an incredible amount of power in a Z car. 300 horsepower in a 280Z is a windowmaker. Good luck!