Upgrading 2011 Toyota Avalon

I'm looking for some help in upgrading the stock system in my Avalon. The stock 7 speaker system is not bad at lower volumes but needs some help.

I want to keep the factory head ( BT, ipod control ) and I already have a couple of amps ( JL 300/4, JL 250/1 ) and a sub (IDQ10).

Would a JBL MS-8 be the best solution for integrating the amps with the factory system? BitOne? Other?

The 9 factory speaker locations are:
Front ( 6.5 doors, tweeters in A-pillar )
Center ( 3.5 in dash )
Rear ( 6.5, tweeters in doors )
No factory subwoofer

Thanks!