Personal opinion is to have a custom set made. I did and they are great. Outside 2 tubes, # 1 & 7, have separate flanges and 2 middle tubes share a flange with removable collector. Makes it much easier to get the in and out. My

1.298 60 ft 6.001 1/8 mile 114 mph 9.52 1/4 mile 140.87 mph @ 3110 lbs