ok do the colder plugs seem to bog down the engine when n20 is not being used(it seems that way for me with the zex plugs) and second what should the idle fuel pressure be set at, mine right now is about 39 which might be low,, any suggestions would be helpful,,,, thank you......Bernie

 

The colder plugs do take away some power when NA, but I never noticed any bogging.... Idle fuel pressure should be 34 psi...

 

Colder plugs shouldnt give you rough idling.

If you are experiencing rough idle, make sure your plugs are gapped correct.

With colder plugs, the car felt more sluggish NA even though i was running 1 step colder plat. plug.