Peel the shrimp, reserving the peels.
In a large saucepan, heat the oil and curry paste until fragrant, about 1 minute. Add the coconut milk, lime leaves, sugar, lemongrass, curry powder, shrimp shells and 3 cups of water. Bring to a boil, reduce the heat to a simmer and cook for 20 minutes. Strain the stock and discard solids. Adjust the seasoning.
Place the noodles in a large bowl and cover with warm water. Soak for 10 minutes, until tender, then drain and rinse the noodles under cold water.
Bring a large, salted pot of water to a simmer. Add the shrimp and cook until pink and curled into a “c” shape, about 3 minutes. Transfer the shrimp to a bowl.
To serve, divide the noodles and shrimp between bowls. Pour in the laksa broth and garnish with pineapple, cucumber, chiles, fried shallots, lime and basil leaves.