As has been mentioned, the twinram is intended primarily for helping evening out the cylinder temperatures. Not making more power
specifically. HOWEVER, the kit's instructions include how to turn up the fuel to allow more power to be made and went as far as including a shaded (color) card one would use to compare to the actual exhaust color when adjusting. (I think for adjusting the AFC).
When it was first introduced, there were no others similar to it commercially available.
As far as the grid heaters, the stock/OEM install has two (2) heaters stacked one atop the other. The twinram kit has one separate the grids and install one in each of the two horn legs.
When installed exactly according to the instructions, it's actually CARB legal and comes with a sticker for the safety inspectors.
And yes, it works quite well with a more realistic 3" plumbing and twins.