I don't really see the comparison to be honest mate... The puma has a 5 speed box that in essence an evolution of the XR box with slightly different ratio's, they have totally different engines and have very little in common with each other.

One of the primary and well documented critisims(sp?) of the ST is the slugishness. The 6 speed is a lazy box on the 170, it's more suited (in my opinion) to the higher power ZT conversions that actually have the power to pull the gearing. With this in mind, this is why I would have thought the closer gearing of the 5 speed box would suit the ST engine and power.