I know when we were looking at buying a 997C2S I need to find car seats that would fit in it and did not find much info so thought I would post. I was able to install two Diono Radian RXT FF. First we removed the seat cushions and backs to protect the leather. Then using the Diono angle adjuster under the bottom of the Radian I positioned the seat and kneeling on it tightened the seat belt down. I have attached a few pictures.

 

I went through this when my twins were younger (now they can barely fit in the back seat) I found it easier if you take out the bottom cushion. I think Graco made a seat that fit pretty well.

 

how much forward did you have to put the drivers seat for them? Looks like they overhand the original seat a bit.
Thanks for the pictures!

 

I already posted this in another thread, but one is an older porsche model and one is a recaro. None of the back seat cushions were removed. I just layed towels underneath the car seats. The porsche fits better, but my girl thinks the recaro is more comfortable.
I think all these car seats hang a bit, including the porsche. The front seats have to be brought in forward a bit.

 

I have tried the Radian RXT in my Cab, but had to keep the cushions in because I found the seat belt was too far forward.
How were you able to tighten it to the back ?
The Radians seem to have a very straight back.

 

Would you mind uploading some more detailed pics? I had the same issue as GAVC with my 996, and now that I'm looking into a 997, I'd like to know how well these fit. Thanks!

 

I use a Diono Radian RXT in my 996 Turbo, which I believe has the same seat size/shape as the 997. I was able to fit it forward-facing without removing the seatback and without using an angle adjuster, and the fit is tight - no wobble. Using the rear tether was crucial, though, so I wouldn't recommend it in a cab. Without it there was a lot of front-to-back wobble. My 35-lb four-year-old is quite happy in it. It provides side protection for his head if I take a corner a little fast, and the cup-holder even fits when the seat's installed. That's one more cup-holder than I have...

 

Here is mine for my 2011 GTS. Seat bottom and back removed, and latched to the top rear behind the seat. It's a britax roundabout.

 

I just went with the Porsche Junior Plus for my 3 year old and a Cosco booster for my 8 year old. Both fit great and didn't need to remove the cushions .