I recently had my IJ apart for a good cleaning and fresh rubber. I have always felt a little unsatisfied with the factory plastic airplanes. So I bought a couple of 1:72 scale diecast planes off Ebay for a reasonable price and fit them onto the game. I know that some IJ purists will say that my planes are not technically correct, but I really like how they look on my machine. They are a bit smaller, much more detailed and look just right to me.......playfield and ramp are also more visible.
I took the LED board and wire harness off the factory fighter and made it work on the new smaller die cast fighter. Basically removed the LED's off the board and hot glued them onto the bottom of the die cast wings. Then cut the original board down so that it was nothing more than a small cluster of diodes and resisters, and hot glued that under the new fighter. Soldered the original harness on at the proper board location, and ran fine wires from the LED's to what was left of the circuit board. The circuit board and wiring is not at all visible when viewing from a normal position.
When the LED's on the fighter are flashing it really stands out a good bit more than what I was used to seeing on the original plastic fighter.
IMO some Pinsider who is good with making and selling mods could probably do a decent volume of business with something similar to this.