You can search the net for copper vs platinum spark plugs.
Sometimes a specialty plug can produce less spark than a standard plug. Which is why most people don't waste money on iridium plugs. I'm not sure if this is different with the rotary engines but every MR2 owner will run NGK BKR7E's which are copper and also 1 step colder than stock. The last thing you want is your car to detonate. You can run 9's all around.

Platinum doesn't wear out as quickly as copper does. I change mine every 3K miles. So for me there's not really a reason to buy plugs that lasts for longevity. Most of the people who use platinum/iridium plugs use them for 10-15k miles.

I have power fc, downpipe, 3" hi-flow cat, 3" exhaust, intake. I get about 21MPG.

 

I think you'll find people in each camp (copper vs platinum), but I'll certainly check up on it. Using 9's all around might not be a half bad idea. I'm not too worried about the money aspect since I only put ~ 2k miles on my car every year.

 

I bought my FD in March. Ive put 12,500 miles on it since the day I bought it.

I commuted from San Francisco to San Jose everyday.

The only problem's I have ever had were flooding issues and fouled plugs. Also ignitor and grouding issues. Other than that good luck.

 

My response was aimed at post #18.

If the FPR is working correctly, it will do this. Because the injector side of the regulator doesn't have pressure, the FPR will stay shut. Don't think "impossible to flood," but "impossible to run."