Hey that looks pretty good my friend. How well do the dive coaster cars keep speed?
They run pretty good as good as the other sitdowns run. But with only 3 cars in a train they have a little less weight.
The track alignments have to be precise. If the train bobbles from side to side it looses a lot of speed. You really have to make proper element shaping and smooth track. Lots of supports to make stiff track.
The trains need a little modify depending on the generation of train you have.
Below is a photo of 4 photos.
1 is where you modify the connection between front car and second row. You dont want much play in the two cars. IF you train has the floor piece like in photo 2 then you are okay; IF not you need a thick section of plastic to make a spacer to tighten the gap. Photo 3 and then make a washer like in photo 4. Insert into the train as in photo 1. Basically stiffening the train so it runs better.