I have the same TTI headers on my 71 Charger R/T 440 AND I have lots of clearance at the number 3 wire . I never burnt a boot anyware and I run the standard plugs. My TTI headers are dimpled already in that area so there is extra clearence. I have had them on the car for 8 years now with about 75 1/4 mile passes without ANY issues. I wonder if you got a very early set. I also run a Firecore set of wires (the set for stock manifolds ) and they fit good .