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but I'll give ya some info that I've read.

Yes, the plugs work with Turbo. read RB site they actually said if u use the older(rx7) plugs u can get a few more ponies under boosted application.

but as always , they die faster than stock plugs. maybe because its platium instead of iridium ?

 

As long as it's not cold enough to cause fouling you should be fine man. The richer the tune, the colder the temp of the tip becomes.

 

7's and 9's are the same heat range as stock, except for the guys that run 6's in the leading spot.

look for brown plugs...nice golden brown.
if they're white, go one or two steps colder.
if they're very dark or black, go one step hotter.

just remember colder is numerically higher than hotter.
ie: 9 is colder than 7