The ngk tr6 is the same as the autolite 104 which is two steps colder from stock.. Is there any disadvantages of running this cold of a plug? mods in my sig

 

I Have Slightly Modified My Motor - Do I Need a Colder Spark Plug?

"A good rule of thumb is, one Heat Range colder for every 75–100hp added." - NGK

 

If you are boosted and modifying, then yes there is a benefit to going to a colder plug.

You don't want the car to detonate at the wrong time, and a colder plug can help with your KR and allow you to adjust the timing.