@nickaix posted:That depends what they are being compared to. Compared to other traditional style Lionel GPs, there is not much difference: none of the GPs are stump pullers. I would not go through the trouble of subbing in a Pullmor power truck for the sake of extra pulling power. You may gain a little, but only a little.
I imagine you could add TMCC to the engine as it is, though I'll leave that discussion to those more knowledgeable.
". . . none of the GPs are stump pullers." Really? I have a Lionel Union Pacific GP7, one of the earliest Legacy locomotives and a Lionel Legacy GP30 from a few years later. Both have vertical can motors and will pull a dummy F7B, an F7A, and 7 aluminum passenger cars without a whimper. The GP7 has slightly less power that the newer GP30. In fact, if I ran the passenger train with the GP30 on the point at full throttle, it would leave the track. Must be the turbocharger that makes the difference. 
Both of these along with my other diesels are just 4-axle locomotives with 2 powered trucks. But they are all powered by vertical can motors. I think today, it's hard to beat the modern vertical can motor for pulling power. With that being said, I don't know why anyone would want to revert back to the more Neanderthal Pullmor motors. Today's vertical cans are smaller, lighter, better responsive at the slower speeds, and just easier to work with in my opinion. 
