I have a stage 2 RSTI swap with around 30k miles. Earlier i looked into my coolant resivuar and noticed it was only about 1/3 filled, and instead of the coolant being green, it was a merky brown color. DOes anyone have any ideas what this could be, my inital thought was a head gasket? I am not sure if i just need to flush the system out and put in fresh collant, or if this is signs of a bigger problem.

get underneath and look to see if the heads are leaking, if their leaking that bad on the inside they should be leaking externaly