Got the sleeve from Aerostich, $30
http://www.aerostich.com/transit-back-pad-adapter-sleeve-1.html

Bought the back protector from RevZilla, $44.99
http://www.revzilla.com/product/revit-sas-tec-back-protector



Old one(standard aerostich back protector) comes out , ...



Compare to the new Sas-Tech back protector



Put the protector into the sleeve, ...





Goes into the suits ...



put the suit on, get on a bike. This is how it looks like from the outside.



Can't really tell there's a (pretty large and thick) back protector in there. It is pretty thick, but it gets softer about a few minutes after you put the suits on.
It's comfortable. Mobility is great. (Actually, standard back protector is also comfortable, and offers great mobility. It's still a great choice for everyday commuting and such. But, for those who like to have fun on the back road,(yeah, you know who you are ...) this is more appropriate application, I guess. )

Nice upgrade.  My only complaint with it is the width, but this one looks better overall...and $75 to do it isn't bad at all.

From a local board, a little FHE (not mine) of how a 'crafter crashes

"I was being a dumbass and wrecked, so I got the opportunity to crash test some of my gear. In case you needed another reason to wear gear, I walked away from this without a scratch. Suit is(was) a roadcrafter with Alpinestars bioarmor on top of the aerostich tft throughout. Also worth mention are my Alpinestars GPX gloves, which got some serious time on the asphalt with barely any damage. Be safe out there..."

http://www.dcsportbikes.net/forum/f19/why-you-wear-gear-79467/

"walked away without a scratch" sounds good to me.  Quality textile stuff provides good protection, but should be viewed as single use. A'Stitch is good at repairing damaged suits as well.