[I assume you have read my methodology for playing Giga Wing:
http://www.free-conversant.com/gaming_journals/2098
http://www.free-conversant.com/gaming_journals/2100 (first paragraph only—describes TANINI's spreadsheet-like coordinate system)]

Purpose. The purpose of this report is to describe how to get a close-to-optimal multiplier increase number in Widerstand's third stage. Today, I'll be describing the section with the third medium-sized plane, which had arrived from the left side of the screen.

Research. TANINI said to use the reflect force (RF) at 6e, so that the medium-sized plane fires its bullets downward. That way, you can reflect those bullets onto the smaller enemies and delay destroying the plane (so that it could fire more bullets). After using the RF, collect the +5 items from the right side before collecting those from the left.

Findings. After I collected all of the items, I reached +1561 in this section. I destroyed all of the aerial enemies in this section and collected almost all of the items.

Enemy behavior: The medium-sized plane will fire another volley of bullets when it's at cell 4d and again at 5d. These are the bullets to reflect onto the plane. Small green enemies (+5) will appear from the top of the screen and quickly move downward. They move in all directions, too, so it's difficult to destroy them all. A few helicopters (+10) will also be on the left side. They will approach you, but if they go to near to you, they will back off.

Option positioning: The options should remain positioned 135 degrees away from the positive y-axis. This way, you can destroy the fast green enemies before they escape while you deal little damage to the plane.

Plane positioning: Position yourself somewhere in the lower right corner such that you can lead the plane's bullets to this corner. I think it's best to reflect these bullets as late as possible, so you should let them stay on screen for as long as possible. (With the previous breakpoint I used, I was too high in the lower-left corner, so I couldn't reach the lower-right corner before the plane fired the next volley of bullets.)

http://shmups.com/beepreying/gj/041226_1b.png
(Figure 1: Positioning and timing of the RF against the third medium-sized plane.)

Timing: Use the left edge of the heliport at cell 7c as a landmark (see Fig. 1). Once the bullets begin to cross this edge (that is, encroach cell 7d), start charging the reflect force (RF).

Movement: Move up to cell 7c, so you can reach the +10 item moving down cell column 7 and the plane. Once the volley of bullets is reflected, move the joystick to the upper-left. This way, you can grab the +1 item shields as soon as they appear. It's crucial not to let them bounce up, because you don't want to waste time collecting +1 items while the +5 and +10 items below you are escaping. Once you're aligned with the plane, move to its right wing. (Don't worry about the items near the left wing—you have enough time to collect these later.) Collect the items there, then the +5 and +10 ones below you, and finally those along cell column 4.

It took me a while to figure this one out...

Next up: the fourth medium-sized plane and tanks everywhere. The goal is to beat +1845. Since I currently have +1561 and I can get over +300 from each medium-sized plane, beating this goal should be easy. The hard part is optimizing this section, of course.