Pantera Electronics is 1st rate! Superior products and EXCELLENT customer service!!!
As already stated, the original wiring in the Pantera is pretty good, but there are some definite short-comings that could cause anything from difficult to diagnose electrical glitches to burning your car completely to the ground!
Known issues with the stock wiring/electrical system...
- Poor and insufficient grounds
- Poor fuse contact/performance due to loose and/or corroded contacts
- Excessive current and heat load on switches in the dash because ALL current runs through the switch, creating a fire hazard. I've heard more than one tale of a melted headlight switch after driving a few hours at night.
- Etc.
ATO Fuse Panel: I've installed a relay kit to take the load off of the switches, and I have the PE ATO Fuse Panel which is FANTASTIC! I didn't have any electrical glitches, but wanted to upgrade my electrical system to be more bullet-proof. Many have reported ATO Fuse Panel upgrade alone solved a slew of electrical gremlins. One of the best features is that there's an LED that lights up if a fuse is blown! No more pulling all the fuses one at a time to test a circuit when diagnosing an electrical issue.
Electronic Ignition System (EIS): I have this too. Another top notch product. 100x faster than an MSD. Will fire a wet plug. Great safety features to save your engine should you lose oil pressure. Auto-retards timing on startup. Will auto-shutoff AC when you stop it to get back that horsepower when needed most. Many other great features.
Console Switch Controller: I have it, but haven't gotten around to installing it yet. I look forward to the auto-open/close functionality that this will add to the window switches.
LED Gauge Lighting: Jon didn't have these available when I converted my instruments to LED bulbs, so I managed to source a decent set of LEDs through trial and error. I recommended Jon add these to his product offering years ago, and he has. I would definitely buy these if you want to be able to see your stock gauges at night.
Temperature Gauge Corrector: I have one from Thomas Tornblom in Sweden - he doesn't make them anymore - so I highly recommend this product to get an accurate reading of your fuel level.
All of the PE upgrades I've made to my Pantera are in the interest of reliability, safety and performance. They perfectly compliment and enhance the existing electrical systems while maintaining a stock appearance. PE also offers many additional and innovative products too that might be deemed more modern or make your car appear less original, but it's up to you what updates you choose.
Cost was a concern to me initially as well, so each year I added one additional PE product that was on my list. This mitigated the pain-factor of placing one big order. And, once I received my first product (and the personal support from Jon that came with it) I was convinced it was well worth the price. I plan to add more of their products in the coming years. 
Anyway, all of Pantera Electronics' products are first rate! You will not be disappointed.