My truck is the 4.2L V6.

 

Exactly what does "custom" tuning mean? Did you do it yourself, did it cost more?

 

It means they custom tweak it to fit the mods you have installed.


If you go to Justin @ VMP, its only $15 more for custom tunes, but he is talking about raising his price.

 

A "tune" is the program written for your car's PCM (computer) which regulates how your car runs. Without getting too technical, let's just say that it's sort of like the old days when guys turned a wrench under their hood. The tune controls, among other things, your air/fuel ratio, idle speed, spark, compression, shift points, et cetera. There are guys out there who specialize in writing new "tunes" to change the way your car runs. You can read more about what they do on their websites. Your best bet is to call and speak with them. There is a specific forum on this website for "tuning".