I just had my car tuned and when i took it to the tuners I realized that the plugs i had in were one step hotter than stock. I have a stock long block 5.0 with a 6psi powerdyne on it. It made 264hp and 300tq at the wheels on a Mustang Dynamometer at york dyno. A day later i talked to some one and they said I should have had 1 step colder plugs than stock for 6psi and 2 steps colder for 9psi. Is this true and if so how much power do you think i was giving up. If the colder plugs are better should I take it back just to have the tuner re-tweak the tune. thanks for an info.
