I just installed a set of the Flame Throwers a month ago after reading posts of power and mileage gains, Also replaced the fuel pump, cap, rotor, wires and iridium plugs. I didn't experience any improvement of either. I contacted the seller and he was happy to do a refund. but I couldn't justify the time and work swapping them back out. They didn't make it any worse.

Like many topics, this one can be controversial.

Upgrades to electrical on a 22 is a reasonable consideration.  My problem is that I have never found any proof of claims by the manufacturers or any dyno tests by someone who has upgraded.

Platinum resistor (low EMI) spark plugs are the best choice for ECU 22s in my opinion.

Most spark plugs have copper cores, but differ in electrode metal.  Iridiums will provide longer life, and known to go 100K miles in new cars with no degradation in performance - my 2013 Corolla has factory Iridiums.  Power and gas mileage gains between copper, platinum, and iridiums is probably negligible, however iridiums are known to fire under more extreme conditions, like lean mixture.  Copper, softer metal, electrode spark plugs are better conductors but will wear and burn quicker than platinum or iridium.

The bottom line is you can spend less money on copper, and change them more often, spend a little more money on platinums and enjoy the ride, or you can spend more money on iridiums and not have to change plugs for 100K miles.  Now, if want to upgrade the stock electrical system to Flame Throwers, MSD, or Crane, I'd would go with the manufacturers recommendations on spark plugs.

I have mostly installed platinum spark plugs in my vehicles and I haven't tried iridium plugs in my 22s but I would like to just for the experience.

By the way, you may have read people recommending or using anti-seize compound on spark plug threads... that is NOT recommended by plug manufacturers.  I have always sprayed just a little silicone lube on the threads and never had a problem.

Also, proper torque specs are important for spark plugs, but just be careful.  My 1986 FSM says 13 ft-lbs.  NGK says 18 to 21.6 ft-lbs for their BPR5EY plugs for aluminum heads.  18 ft-lbs on my torque wrench starts to feel a little heavy for me. Cross threading spark plugs in a 22 seems not uncommon.  I always look at the slight angle of each cylinder in the head as I install spark plugs.

Keeping the cap & rotor fresh is important on these 22s.  I like the solid core plug wires.

That's just my worthless opinion.

Gnarls.