Every school teaches different topics in GMA, so I can't tell you what's relevant until I see your syllabus for GMA.
The topics for Specialist Maths are, in no particular order:
1) Graphs - Ellipses, hyperbolas, reciprocal equations (such as 1/(ax^2 + bx + c) or 1/sqrt(2 - x)), summing two functions (such as 1/x + 1/x^2)
2) Vectors - Parallel, perpendicular, dot product, vector proofs (such as proving the cosine rule using vectors)
3) Complex numbers - Cartesian form, polar form, De Moivre's Theorem, solving polynomial equations with unreal solutions
4) Algebra - Simultaneous equations, parametric equations, some inverse functions involving domain and range (though most inverse functions are taught in methods)
5) Circular Functions - Trigonometry, solving equations involving sec, csc, cot, asin, acos, atan, evaluating things like sec(pi/12) using double angle formulas and addition/subtraction formulas
6) Differentiation - Power rule, product rule, chain rule, quotient rule, implicit differentiation, second derivatives. Also applications involving optimisation and finding stationary and inflexion points
7) Antidifferentiation - Definite and indefinite integration using substitution, partial fractions, splitting up the integral and recognising things like trig functions, inverse/reciprocal trig functions, natural logs, exponentials. Also applications involving areas under curves, areas between curves and volumes of solids of revolution of either the x-axis or y-axis
8 ) Differential Equations - Slope fields, separable differential equations that can be turned into the form ∫ f(y) dy = ∫ f(x) dx, verifying solutions to DE's by substitution.
9) Kinematics - Acceleration, velocity, displacement, speed, velocity-time graphs, using formulas such as a = dv/dt = (d^2)x/(dt^2) = v*dv/dx = d(1/2 v^2)/dx, solving long worded problems
10) Vector Calculus - Position, velocity, acceleration at time t, solving problems like "the path of a particle is... how many times does it cross the x-axis in the first 2 seconds?"
11) Mechanics - Using F = ma and a few more formulas, solving equilibrium problems, ramps, pulleys, motion
I can't guarantee that I didn't miss a topic (it's been a while), but this should give you a pretty strong indication of what is in the specialist maths syllabus.