No cutting was needed. I gave TTI my manifold numbers and the system fit perfectly. My manifolds are the restrictive 72-73 ones but the car is just a cruiser. I may still go with some TTI longtubes down the road.
Sorry. I went TTI shorty headers. The directions say H pipe might need to be trimmed? I was just asking if you had to trim anything. I love my system from them. Money well spent.