Your DI unit utilizes a "downward pointing" piezo to obtain data for the DI image...
Your SI unit utilizes the 2 "side pointing" piezoes and then the processor rearranges the data to look like a DI image view....
You can obtain a little better DI images in your SI unit by passing over structure to side of the structure just a little ...preferably putting the structure just to the right of vertical...
This will put the structure closer to the center main axis of the right SI beam ...(which is the strongest part of the right SI pulse...)
(The "down pointing" piezo of your DI unit has it's "DI beam center main axis" pointing straight down...reflecting better off structure directly under the xducer...)
Rickie