Ok im putting new plugs in and ive done this a couple times but ive always gotten confused about the gap since it says .039-.044 whats a better gap?

Btw they are NGK Iridium's

And i dont know if mods affect the better gap but i have a RRM pulley and Intake....

 

That is simply a range, as long as you are within it, your car will be fine. I doubt there even is one single perfect gap, or that a person could notice if they had it.

 

So would what be better bigger or a smaller gap?

 

Go with the recommended range. As long as you are within that range, everything will be fine. You don't need to fiddle with the gap until you start heavily modifying the car.