Let's have a look and argue like nerds over this, shall we? I got the pre-1.6 stats from here. I read elsewhere that some have been moved around in the tech tree.
Wolfhound
Cost: from 1,680 to 3,000 +1,320
Mass: from 2.5t to 3.3t +0.8t
ISP: from 70asl/412vac to 70asl/380vac -32vac
Thrust: from 63asl/375vac to 69asl/375vac +7asl
Cheetah
Cost: from 1,000 to 850 -150
Mass: Unchanged
ISP: from 150asl/345vac to 150asl/355vac +10vac