Some NewGRF trainsets, that replace the maglev track with narrow gauge rail, have problems with their visual effects and sound effects. With both the Serbian Narrow Gauge set and the narrow gauge trains in the Canadian set, the steam trains and diesels show no visual effects and all narrow gauge trains have maglev sound effects.
This patch fixes these problems. Visual effects are now based entirely on Action 0 property 0x22 (visual effect type) for NewGRF rail vehicles. Default values are given to original vehicles. Sound effects are now based on Action 0 property 0x19 (traction type) rather than the rail type.
Hopefully I haven’t messed up anything but, as usual, I make no guarantees.

With my update to the Narrow Gauge rails grf it makes both the Canadian and the Serbian Narrow Gauge sets more playable in OpenTTD.
Edit: patch updated to r8832. 21/02/07
Edit: patch updated to r8907. 26/02/07
Edit: patch updated to r8984. Some problems with Serbian set Pendolino fixed. 02/03/07
Edit: patch updated to r9072. Tilting effect for Serbian set Pendolino added (action 2 var 45) 08/03/07