Narrowest HBB for 6.5 year old (three across)

[kittykate]

O is outgrowing the Radian in DH's car, so he will need to start booster training to ride in a HBB. Right now we have a tight 3 across (ff Radian, FF Radian, RF Marathon Classic) in a 2005 Hyundai Elantra and I need some thing that will fit where the outboard radian is currently.

From the measurements spreadsheet, it looks like the Turbo Booster is a good bet, but I'm wondering if it will be a good value for a 6.5 year old or will be quickly outgrown.

Any suggestions for a narrow HBB?

 

[joolsplus3]

Turbo is SO deceptive...narrow on paper, but just about the hardest thing to buckle next to another seat
Harmony Dreamtime is pretty narrow, not too tall in the back, but inexpensive enough for now... http://www.target.com/p/harmony-dreamtime-booster-gray-black/-/A-13981482
And the Boost Air Protect is narrow at the belt path, with flip up armrests, I like it for 3 across (and it's super duper tall, but requires a head restraint behind a tall child, so bad in a car with a bench with no headrests) http://www.overstock.com/Baby/Safety-1st-Boost-Air-Protect-Booster-Car-Seat-in-Newsboy/6593106/product.html?cid=202290&kid=9553000357392&track=pspla&kw={keyword}&adtype=pla

 

[thepeach80]

Our top choices are the Air Booster and Amp/Big Kid. They have big areas for buckling. The Dreamtime fit, but there was no real way to buckle it b/c of the armrests.