There are 2 companies that make Aluminum Rockers for the Nero platform, that I know of. Hot-Racing and GKA Customs, I will put links for both at the bottom of this post. As far as I know GKA doesn't have a website, but they are one of the listed vendors and are very active here on the Arrma Forums. I went with the Hot-Racing rockers, but something to be aware of is that the Hot Racing rockers are a very different design and are probably not as strong as the GKA Rockers. Rather than trying to explain the different I would say take a look at pictures of both and you will see the difference in the design. I went with the Hot Racing rockers because I was trying to resolve the issue with the stock shock spring retainer hitting the rocker arm and it looked to me like the Hot-Racing rockers would have more clearance. Shortly after buying them a couple of people here on the forum also suggested replacing the shock spring retainers with the Hobao Hyper Shock Damper kit #90049. You don't need the whole kit, but they don't sell the shock retainers individually. Once you put the Hobao shock retainers on there is no more clearance issue with the shock and the rocker arm regardless of which rocker arm you have.
The very first part I broke and looked to upgrade on my Big Rock was a suspension arm. In the first 20 minutes just out of the box I broke a lower rear suspension arm. So I started looking and asking around for aluminum suspension arms, but I still have not found anyone who is making them for the Nero platform yet. Unless you know someone with a CNC machine and the time to build the design file for all 4 arms I think we are stuck with the stock plastic arms for now.
Hot-Racing Rocker Arms NRO27M01: http://www.hot-racing.com/index.cgi?partnumber=NRO27M01;c=1019
GKA Customs Parts List: https://arrmaforum.com/threads/nero-rocker-arms-and-big-rock.1947/
GKA Customs Vendor Forum: https://arrmaforum.com/threads/gka-products.2696/
granted the first break was me being dumb hah
