I've had my kids riding in my Cobra since they were 3. Carseat is a little bit of a pain to put in with the racing harness, but I can get it just as tight as the seatbelt in my daily driver. Only problem I have is I have two kids, and I can't take them both at the same time, so they're always fighting over who gets to ride in the Cobra
As loud as the car is, you'd think it'd be hard to sleep, but it always seems to knock my 4-year-old out:
Pete