shorter longer or the same length as the first restrictor plate 10 as indicated above an example of a longer restrictor plate 82 is restrictor plate 67 illustrated in fig3 it should be appreciated from the above discussion that the shape of the restrictor plates are symmetrically designed this symmetry provides advantages discussed below the second restrictor plate 82 is positioned forward of the first restrictor plate 10 and is substantially flush with the inlet 12 this is because the second restrictor plate 82 does not extend over the grate 36 the aggregate length of the first and second restrictor plates 10 82 are intentionally less than the width of the inlet 12 this enables the two restrictor plates 10 82 to be connected by a splice plate 84 providing end to end restricted coverage of the inlet 12 the splice plate 84 is formed from the same material as the restrictor plate 10 as illustrated in fig4 the splice plate 84 has the same height as the restrictor plate 10 the splice 84 plate is formed with compound i e two offset angles 86 88 such as a shifted slide as illustrated in fig4 based on the first offset angle 86 one side 90 of the splice plate 84 is lower than the other side 92 based on the second offset angle 88 one side 90 of the splice plate terminates rearward of the other side 92 this compound offset matches the downward pitch of the throat 22 occupied between adjacent restrictor plates 10 82 as a result the two restrictor plates 10 82 engage in a linear connection across the inlet 12 the splice plate 86 is formed with opposing end tabs 94 96 the tabs are parallel with each other and at an angle 99 to.