I see that they are gapped at .050 from NGK should I be leaving it at this size or opening up to .055 that I have seen others do? My car is boner stock as you can see from my sig but I have much in the works and would like this to be workable with growth. Obviously when the heads go on the new plugs will be put in again, and at that time if not now should they be gapped greater? Thanks!

 

Don't they come pre-gapped at .055? I know mine did (2 different sets). I'd leave them gapped at the .055, I doubt opening the gap would help any. I've got mine gapped at .055 with the mods in my sig, and she idles just fine (except for that slight lope).

 

TR55s actually come pregapped at .059 according to NGK, the TR5s come in at .039

You should not change the preset gap by more than .01, so if you want a .029 to .049 gap, run TR5s or TR6s, if you want a .049 to .069 gap, run the TR55s.

I've always felt the LS1 likes it's plugs in the .045 to .050 range, not the .060 stock spec.

 

I have seen on the sponsors sites that they are being sold from .050 to .055 so I guess what they come in at will be what I will leave them at. Sound about right? Mine too will have the 'slight lope' with the 224/224-114