Analysis of using encapsulated extensional rheology and step-strain to fit the non-linear parameters of the multimode pom-pom model is examined for a series of HDPE sparsely branched resins. The information available on these materials offers an excellent opportunity to compare our predictions to and aid in the possible determination of a more unique set of parameters. A novel encapsulation technique designed to overcome ductile failure in extensional flow shows promise for gathering data at higher strains, thereby improving model parameter fits. Differences in the behavior of the relaxation modulus at short times following step strain is seen as a function of LCB content.