In a saucepan, combine sugar, eggs, lemon juice and salt; cook and stir over medium heat until temperature reaches 160 degrees and mixture is thickened, about 4 minutes. Cool completely. Cook spaghetti according to package directions; drain and rinse in cold water. Place in a large bowl. Drain pineapple, reserving juice. Pour juice over the spaghetti; stir in apples. Toss gently; drain. Stir in the egg mixture and pineapple. Cover and refrigerate overnight. Fold in whipped topping just before serving. Garnish