could this be a slash/non slash thing?
Maybe the Pro and Khaos non slash models have the storage, and the slash models don't. This would also explain the length differences of the tunnel coolers compared to the seat if the slash models have a shorter tank/seat.
It’s actually the opposite effect of what you just said.
The slash cooler ends at the seat and the standard matryx goes 6” past the seat.
Slash and matryx both have the same seat/tank combo.