Quit using them 90's at the spark plug and use 45's. Not all need 45's tho. usually a set comes with 2 or 3 wires that have a 45 angle.
Last set i had was for a '66 289 and had 3 45's (plugs #1, 4 and 8). Got new set this week for '66 289 with smog and only 2 45's at plugs.
Edit: i didnt read your post slowly enough, idk if 45's will help or not with the headers
Last set i had was for a '66 289 and had 3 45's (plugs #1, 4 and 8). Got new set this week for '66 289 with smog and only 2 45's at plugs.
Edit: i didnt read your post slowly enough, idk if 45's will help or not with the headers