I'm putting NGK TR55's in my 89 camaro, im wondering what gap I should go with. I have a 305 w/ dart al heads, msd digital 6, msd blaster coil, stock dist w/ accel cap and rotor (msd dist needs to be fixed), kn airfilter, msd 8.5mm super wires, etc. I've been searching and i've seen that stock is .035, but I could go to .045 b/c of the msd? Is that a good idea? What gap should I use? I may just compromise and go 40 or 42, i dunno whada you guys think?

 

most efi cars I would use .045 more often then not.

 

With stock compression and the MSD setup it should have no problem at all with .045" .

 

I have performance pistons in there I think the compression is a little higher since I have to use half premium half regular, does that make a difference? Is .045 ok? Should I do .040? I only want to do this once

 

.040 should be on the safe side for higher than normal compression with the MSD setup. The only difference between .045 and .035 is a minor difference in emissions when the engine is cold. No real difference in performance compared to the difference between stock ignition and the MSD.