Hi there everyone. Cages are probably one of my favourite topics. I've recently completed a homologated cage for my coupe. 40mm steel Tube cost $150 and it is far superior to any kit set cage you buy. The trick is to have the cage as close to the body as possible and kit cages don't have that tolerance. This cage is tied into the A and B pillars and has a cross bar under the dash and permanent X intrusion bars on both sides. The rear stays go to the inner guard as you are usually not allowed to go past the suspension points front and rear. I have a horizontal belt bar between the rear stays and a diagonal from the driver's head to the passengers rear stay - this forms a triangulated structure that is heaps strong over the drivers area. Another horizontal bar runs above the front screen. You can mock your cage up with PVC pipe or wire to get the bend angles right. All bending was done with a hydraulic former - the trick is to full the tube with sand, tamp down, top up with sand, tamp again until no more sand can be added and then mig a plate over the end. We then heated up the pipe over my new barbecue and coated the part to be bent with grease. You have to measure your bends with a micrometer - if it crimps then it won't be strong and won't pass homologation. Attach the A and B pillars with a bit of plate. You end up with a cage that offers great protection and really stiffens up the chassis. The kit cages are usually free standing with oodles of room between them and the interior. If you do have a major stack then the body deforms and then hits the cage with impact - sort of like a slide hammer action. A custom engineered cage is part of your body structure because you spend time getting it close to the roof and pillars and tying it in to them. You will need a ticketed welder to do the welding and then sign off on the homologation form. It can be a lot of work but if you have the time and want to have the best result get into it. A lot of laughs can be had slowly rotissering a 5 metre legth of tube over a BBQ at 2 in the morning!