Insurance in the US is not like Europe/Aust. Hit a pickup with people in the bed in the back, you are still on the hook (complicated but this is basically the answer).

I have zero doubt that it can be done safely. The devil will be in the details (like what the mounts look like and whether you need to weld reinforcements under the body). I have taken apart numerous cars and the seat belt mounts vary greatly, but it is not rocket science compared to what people do to cars.

I have looked into this before and agree with the others. It can be done safely, but too many insurance issues in the US. Best call is to get a 991 turbo or GTS. If u have to get a GT3 (which I realized I did), get another fun car to haul the kids

What insurance claim do you think you will have if you are in an accident with your own kid in the back? That you may not fully recover against another driver for injury to the child? An unisured/underinsured motorist claim on your own policy that won’t pay out? That your child will sue you when he/she turns 18? I suppose if you are cautious you probably should not take someone else’s kid back there (even that is debatable), but what claim are you worried about with your own kid? Keep in mind you are driving around where the vast majority of people are underinsured if they hit you in a GT3 from a property damage standpoint let alone injury and are judgment proof.

And this is even assuming that there could be a showing of contributory negligence in the seat install (seems unlikely that the seat/seat belt would fail).

And no such thing as an engineering certificate in the US. That’s an Aust/UK thing.

Back on topic, does anyone have pictures of the back of a 991 non-GT with the interior removed to see what the brackets look like?

There are limited regulations related to safety standards for car modifications in the US. States have things like maximum bumper or light heights and things like levels of tint that are legal and most (not all) states have safety inspections which check for things like you have seat belts, 2mm minimum tread on tires, and brakes that work (standards are usually low), but if you wanted to, for example, graft your GT3 body onto a lifted 1980s truck frame in your garage, no one is going to stop you.

Frankly, if you saw what rolls down the road legally in the US in many cases you would be appalled. Our European members worry about (and can’t legally) fit the correct size tire in a brand that is not certified for that model. In the US you can bolt 44in diameter tires on to a vehicle originally fitted with 29in diameter tires.

I’d look into this very carefully before committing as I believe it would endanger the child. The stretch of the safety belts or mounting straps used to secure the child seat are a key part of the safety package insuring that deceleration Gs are tolerable. More give is better (as long as displacement isn’t enough to hit something).