First install for Radian RXT booster

[RiverRat]

I just purchased the Radian for DD 6 years old 53 pounds and I'm going to install it in booster mode. She's been on 5-pt up until this point in a Frontier.

My questions:
When I snapped open the base it seems like there is extra foam where the lower back would go. Is this normal?

Do I still use the top tether when installing in booster mode? I know I can use latch to keep the seat in place so it doesn't fly around.

What is the Safe Stop strap I see at the top?

I've read the manual but I couldn't find these answers.

This is being installed in a 2010 Honda Ody in the 2nd row.

TIA!

[legaleagle]

Safestop is only for ff'ing harnessed kids who are under 40lbs. Not sure about the other questions. In general though, the radian isn't a great booster -is there some reason you bought it in particular?

[Joolsplus2]

Ditto.
I Yes, the tether can be used in booster mode, and usually foam in seats is meant to be there.
Make sure the belt retracts safely over her after she leans forward, here's a picture of it staying slack on another kiddo (scroll down...) http://carseatblog.com/14805/diono-radian-rxt/

[RiverRat]

Safestop is only for ff'ing harnessed kids who are under 40lbs. Not sure about the other questions. In general though, the radian isn't a great booster -is there some reason you bought it in particular?

I have limited options in Canada for seats to choose from and needed a seat I can put back to harness for longer drives. I also needed the narrowness of the seat. And it was on sale.

[Joolsplus2]

ah, gotcha!