Small Problem (Hesitation) After Installation of JWT Hotshot Header

[Frank Ewald]

I agree that you're modifications shouldn't be doing that. And I  
would wonder if your ECU wouldn't just be dead if it was shocked by  
welding - but I'll leave that up to the electrical gurus.
I don't have answers, just questions:
When you changed the plugs/wires did you use OEM or 3rd party  
equipment? Did you ensure that they are tight still? (I know, silly  
comment but I've seen spark plugs just bouncing in the head and  
obviously not firing properly.) Have you changed the fuel filter? air  
filter? Is the stutter at a specific speed/rpm or random? Continuous  
in that once it starts stuttering it maintains it or is it just for a  
short time?  Is the intake stock or modified too?

That's as technical as I get. You've done some similar mods to your  
GA'd NX as I have done.
Have fun.
Frank