I've been told (and agree) that the NGK 8's are the plug to run on my 408 (11.7:1, Texas giant cam, PRC stage 3's) but on motor only would it run better on TR6's? I'm not gonna spray it for a couple track visits until I get used to the car more and work out some bugs. Driving it around town it seems lean, kinda stumbles with the NGK8's at .030. Don't recall it doing that with TR6's, but didn't drive it much with those in it (just got car).

Just looking for more streetability with this big cam and stuff.

 

We run the 7's in mine on motor but the compression is up. You'll be fine with TR6's on motor.

 

To run the colder plug you need to lean it out at idle and put some timming in it. this will help alot.

 

I ran the same mph n/a with TR6's and NGK 8's. Have put a couple hundred street miles on the 8's and they're still fine.

 

Right, as long as your idle tune is good there should be no real difference.
Thats why we always try to tell guys to run 1 step colder than you think you need. Cost is about zero hp but it could save your motor.

 

The previous owner ran TR6's all the time, even on the bigger shot. So I'm sure its tuned for that. I'll swap in a set and see if it runs better, any idea on where to set the gap for N/A?

I plan to retune at some point, just not yet. My tuner is a few hours away.