lower softening points were obtained as will be seen in the example in contrast resins obtained from polymerization of the piperylene rich feedstream only no addition of the modifier stream have mw of about 1600 undesirably high the best mode of the invention described herein is exemplified by the following sequential processes of isomerization admixing polymerizing and resin recovery a a branched olefin modifier stream obtained from a solvent extracted c 5 c 6 isoprene rich stream of steam cracked naphtha typically composed of 3 wt isoprene 57 wt c 5 c 6 olefins 35 wt 2 methylbutene 1 and 5 wt 2 methylbutene 2 was admixed with an isomerization catalyst amberlyst ir 15 available from rohm and haas philadelphia pa at a rate of 1 volume of said stream per volume of catalyst per hour at 40 u00b0 c to provide the branched olefin enriched modifier stream the resultant enriched modifier stream had a typical composition of 3 wt isoprene 57 wt c 5 c 6 olefins 5 wt of 2 methylbutene 1 and 35 wt of 2 methylbutene 2 b 4 volume percent of said branched olefin enriched modifier stream was admixed into a piperylene rich feedstream 15 wt piperylene with minor amount of isoprene 25 wt of c 5 c 6 olefins 4 wt of 2 methylbutene 2 and balance diluent.