zincsvtcobra

I am planning to change my spark plugs on my 03, but all these plugs have me confused. I see that most run NGK TR6, which is what I bought, but why are the cheapest plugs the best for a 400HP plus car? I guess I want the best plugs for performance and to decrease my chances of detonation. Are the coppers really better than a platinum or iridium plug? Also, what are the rest of you gapping your plugs at? I've heard .040 from PHP, .030 from 50 magazine, and of course factory settings at around .050. Thanks for the feedback.

spray175

Alot run the TR6's. I just bought them too. I hear alot of people say its not worth the $$ for the other plugs. Also most people with cobras gap them at.035-.038. Correct me if im wrong somebody.

NightmareStang22

Go with the TR6's! Seriously, nothing else. We put some iridiums in my buddys 03 Cobra and had it dynoed. It hit about 370! Man it was bad, so we went to autozone bought some TR6's, put them in and and it got dynoed at 442. Plugs make a hell of a difference.

Cloud 9

TR6

FTW!

CobraBob

Iridium are excellent plugs. Just a bit more fragile. And you have to check the gaps from the factory because it is common that the gap varies. I had Denso Iridiums on my '03 Cobra and made a bit more power than the average for the mods I had. They were gapped at .034. Believe me, they work. That said, IMO the best overall plug is the NGK TR6. Easy to find. Inexpensive. And they WORK! Which is why they are probably still the most popular plug IMO.

Here is some good info from the NGK website. Improper gapping can, of course, affect performance.
Always check that the spark plug gap is compatible with the engine manufacturers specification. A gap that is too small means that the spark duration will be very quick and the spark will be thin and weak. The consequences of this may be bad starting and high exhaust emission levels. This will result in an increase in fuel consumption. If the gap is set too large, the ignition system will not be able to cope with the demands and a misfire situation will occur. Some wide gap spark plugs have a longer ground electrode to accommodate a wide gap setting. These must be used where specified, as opening up a standard plug to a wider gap setting may result in the electrodes not running parallel to each other. This could result in abnormal and premature electrode wear.