i just wondered what spark plugs you all are using and specifically what you are using with an MSD ignition system (box, coil, and/or opti) it seems that my car doent like what i throw at it. i put long tubes on it this winter as the only change i made and all of a sudden a low end miss occaisionally occurs but disappears when i throw a new set of plugs at it for about a week.. then it returns. i've had NGK tr55's, and now autolite double platinums. im tired of throwing $20-$30 in plugs at it and an hours worth of work every other week. let me know what you think. is it maybe that the tune i have is setup for mid length headers??

 

How about the plug wires, have you replaced those?

 

the plug wires are msd units as well and are very fresh.. little more than a year old. they wouldnt be bad already??

 

Doubt the wires are bad then. You mentioned this problem happened after installing headers. Sometimes with coated headers, they tend to take out the 02 sensors.

 

I agree it sounds like a problem, other than the plugs....

I am running:
MSD Digital 6
MSD Blaster Coil
Taylor 10.5mm wires
Stock Opti
NGK TR6 plugs...have also run the TR55's (removed all ability to spray, while waiting for a rear end)

 

After the low end miss comes back...take the plugs out and re-gap them @.030...

Dennis