Here's some advice. I assume like most people you plan on modifying the car. You need to wait until you understand ALOT more about cars or you will waste a ton of money and time.
I have a cheap aluminum radiator, exact same thing happened to the trans cooler fittings on it. No way did I over tighten them, they were just shit fittings.
Back on topic. How much time would you actually save when changing plugs anyway without the crossover pipe? 5 minutes? Then factor in how long the install of a ffp takes. ......
And here's another thread about a misfire with a wasted spark setup. Have you set the dwell to suit the coils? Did it miss before the ways spark setup went on?
If you put a pressure gauge in the fuel reg port it would show the same psi reading as the rest of the gauges on the inlet ports based on sealing off the ports.