upgrade tires/shocks OR cold air intake and cat back exhaust

I have a 2014 Tundra Limited and tow a 31' Forest River Pull Trailer Toy Haul, to haul my HD Tri Glide (weighs 1200 lbs) The trailer GVW is 10,500...so I am at max weight.
I installed Firestone Air Bags and they really help the ride and have an Equalizer weight distribution hitch. My concern is I travel north and south through the mountains and want the best option for my Tundra to handle the towing. I an only afford one of the two options:
1. Install a cold air intake and cat-back exhaust OR
2. 5100 Bilstein Shocks and 275x60 -20 tires
Your recommendation will be much appreciated.

 

Skip the intake. Get a bam mufflers exhaust in the group buy, last week to get a killer price!

As far as tires, if i had a trailer that big, E rated tires would be my very first purchase for the truck