the shock tower interferes with #1 and #2. The #1 tube required a decent amount of clearancing, not just a small dimple here and there. Also around the starter bolt; a little odd, since these were used and had been installed on a previous car- the head to header to starter relationship is not different. The motor assy (with headers mounted) is sitting perfectly centered between driver side and passenger side interference areas. Any further one side or the other and the tubes would require significant 'pursuasion'. The crankshaft centerline is not perfectly centered in the chassis, but its way closer now than it was with the manifolds and the previous owner's engine swap.