Not a gd idea, Y any one would want to put alto/mehrans spring in a coure?
springs and the shock absorbers work in exact collaboration with each other, springs resist the downward push and shocks resists the upward push of the spring.
thats y strong spring needs a strong shock to equalize the force and absorb shock.
coure confort level is way better than the other two you mentioned and it has independent rear suspension which offers better road grip.
check your suspension checked properly and replace with OEM as necessary.