.5 is not gonna matter .. 8mm will fit into the stock wire looms , 8.5 mm will not, then you gotta upgrade the wire looms.. Plus if you ever decide to get the MSD box 6a then you will have the plug wires already on.
going from stock wires to 8mm or 8.5 mm wires the engine will rev more freely...
then after all of this is intalled theen u can have fun playing the gapping game..lol

 

really....wouldnt have guessed.

What are the wire looms and how do i upgrade them. Oh and I already know the gapping game...fun stuff.

 

so what u getting?

 

I want msd, id get the 8.5mm but im not sure what else i need so swap to install them. So ill prolly research and if i cant do it quick ill settle for the 8mm for now.