It would actually be harder to smoke 'em up with bald tyres because there is more rubber in contact with the ground, acting like a slick tyre. the tread is there only for when it rains so to channel out the water. Mate you might be heading in the right direction about compression, also don't forget the difference could be a number of things, fuel, temp, and different dyno, it only takes couple of differences and they all start to add up. hey keep us posted as i'm about to spend some cash on my 33 soon.