spark plugs
You can gap any plug to whatever you want. The main difference between the TR55 and TR6 (is that what you meant?) is the detonation temperature. Most people use NGK TR55's for an engine without power adders, and TR6 for nitrous appications. I think that the TR6 is usually set to a smaller gap (.035) on a nitrous car as well.
NGK tr55 are the best you can get for stock or tuned motor N/A(i noticed a huge diffrence in them and oem) but tr6 is at 35 for power adders and gives you bad fuel economy (burns the fuel badly)
My take on this is because everything that uses a .050 stock gap is usually speced for platinum plugs like we are so it is just us enthusiast that want copper plugs gapped that wide, people who are just maintaining a car will go with the speced platinum. Autolite 104/106 are another good alternative. With the iron heads of the b-body some have found the 106 to be a little hot so we use the 104s(103 with nitrous) but the aluminum heads seem to like the 106 fairly well, plus side is these are as easy to find as a Walmart.


