I have to agree with Matt on
 

I have to agree with Matt on this one - intuition tells me this is just a gimmick, but I am interested in seeing results.

If this theory of more surface area on the electrodes yielding better spark is true, it surely has diminishing returns, for as you increase the surface area of the electrodes, you are essentially making it more difficult for the mixture to get to where the spark is going to occur at, and also with larger electrode surfaces, you're less likely to know exactly where the spark is going to occur.

As for my input on the drawings, perhaps they are showing with those 'islands' the isotherms [lines of constant heat, like in a topographical map] generated by the sparks, although by looking at the crudeness of the drawings, I doubt there was any serious testing invovled to determine this. The flame front does propagate from the spark plug region of the combustion chamber, but I highly doubt it must make a 90* turn to go around the ground strap on the plug - it probably just splits and meets back up on the other side.

Again, not trying to say they won't help, I'm just very skeptical.

Actually I'm a little
 

Actually I'm a little skeptical myself. But I figure it's worth a shot to see if they just might work. I'm going to top off the tank tonight so I can get some figures on the new plugs.

My thinking is if you want a
 

My thinking is if you want a stronger spark then get a stronger ignition coil.

When I had a MSD system I had a MSD blaster SS coil. I disabled my internal coil and used the msd coil. From 2000-4000rpm there was a difference in performance. The rest of the rpm was like on the original coil. I never checked the mpg when I had the msd system because the car was built for performance. I'm sure you'll get maybe 1-2mpg increase if you switch to a stronger coil.

The cars without distributors you can buy a device which will make your coil packs have increase voltage. But with more power to the spark plugs you got to upgrade the spark plug wiring. Upgrading the coil and not the wires will just deteriorate your wires and you won't see any increases in your mpg or performance.

On the '89 240SX I installed
 

On the '89 240SX I installed a Jacobs Omni Pack coil and Jacobs wires. The instructions say to open the gap to about .045 then open even farther in .005 increments until a miss is detected, then close by .005 increments until the miss disappears. After this process, I gained about a mile per gallon and low speed and idle was noticeably smoother. No doubt the extra spark energy (it has a 30 amp fuse) and the multistrike spark helped. The OEM gap I think was .035 and I ended up at .055. When I removed the Jacobs system to sell the car, to my suprise it still ran almost as well with the stock system and plugs gapped at .050. Didn't get a mileage read with this set-up, but it may be worth further investigating.
Speculating about why this is so, I'm inclined to beleive that spark gaps are like ignition timing, the factory plays it safe to cover degradation of components and poor engine tune tolerance. If the gap is increased to the limit of the current engine configuration there may be some gains possible, but degradation of the state of tune may have a greater more immediate effect.
An electronics tech/motorhead here at work thinks that the stock system might not be durable drawing the extra current needed to jump a large gap. Any EEs out there know what parts of the ignition system are the most likely candidates to fail while drawing greater current with an increased gap? Coil, ECU?
I'm experimenting with increased gap right now on my B2300, but since it has dual plug heads it's really hard to detect if one of the plugs is not firing. Lean burn tolerance is pretty good though, the EFIE is pretty well cranked, I'll take a voltage reading soon.

https://www.haloplug.com/faq.php
 

So I just read about these Halo plugs in the BetterMPG group - did they work at increasing MPG??? The idea is to change the flame front to ignite the fuel faster and better thus getting a more complete burn of the charge and more quicker to get the fuel producing power at the top of the power stroke. Sort of like indexing the plugs without indexing them by shooting the spark out straight from the tip . . . fire ring plugs used to do the same thing but these seem to focus the spark better.

Re: https://www.haloplug.com/faq.php
 

I think they are working; somewhat. The reason I say it that way is, as I was just mentioning to someone recently, that I started testing them during the winter months. I haven't really seen a big mileage increase but it doesn't seem like I have taken as big a mileage hit this year as I did last year. According to my gaslog, I'm averaging just shy of 40 mpg but last winter my mileage was closer to 36-37.

but were the temperatures
 

but were the temperatures the same last winter? it's been milder this winter, where i live anyway.

Re: but were the temperatures
 

You may have a point there. I'll have to see if I can dig up some figures for last year's temps. Unfortunately I'm not so good at keeping track weather conditions/temps. :-(

mileage
 

Well temperature really has a small effect - I just went around my usual Ocean Drive at noon time today 14-20 degrees outside and started cold but got 42.3mpg . . . a few days ago on the 45-50 degree day I got 44.0 and it was windy and raining wet roads daytime . . . so go figure . . .

i guess it depends on what
 

i guess it depends on what you consider "small". 42.3 to 44 is a 4% difference (from the lower figure).

personally, i'd call that pretty significant!

many of the individual mods we make to our cars don't return a 4% change.