Differences between METIS 4.0.1 and 5.1.0


I have been happily using METIS 4.0.1 for while, but recently switched to 5.1.0 for better 64-bit compatibility.
However, for smaller graphs, which shouldn't have issues regarding 32 or 64-bit stuff, I am getting worse partitions (data clusterings in my case) than I used to get with the 4.0.1 version. Which parameters should I specify to gpmetis in 5.1.0 in order to get the same behavior of pmetis in 4.0.1 (defaults)?