I have a 2014 Hawk. I outfitted it with 40# struts front and back. I have the full Yakima rack with basket and a 100 watt panel. The 40# struts are perfect and sometimes I need to coax them down.
The ball sockets used are 10mm and can be found at a good auto parts/hardware store (not O'Reilly's or Autozone). They can also be bought online but I felt more comfortable grabbing them at a store where I could check and make sure they fit.
If you find the Suspa model number you can put it into the eBay search engine and find an off brand for a way better deal. I got two pairs of 36" struts for $29.99 per pair with free shipping. Work great. I definitely would not buy heavier than 40# with the new threaded system. If people are having problems with the factory install then I would guess heavier ones would cause damage much sooner. I ended up having around $100 invested compared to the $300+ charged by the factory. Good luck!!
Chris
Sorry, just re-read your post and saw you have a 2011 which is prior to the threaded sleeves being standard. The angle brackets you will need are readily available on eBay and other sites. It should still be 10mm.