I don’t know if you have done it yet but if I may offer some recent experience talk
2 inch to the Y section 2.5 inch there after one 2.5 inch cat one straight through muffler, one resonator it sound brilliant but way to loud and you loose to much back pressure however your motor revs like a formula 1 race car.
You need something with a baffle even so it’s still plenty loud but you have back pressure on a D1 with out a cat I would have 2 to the Y then 2.5 there after a resonator a straight through muffler and muffler with a baffle for a D2 much the same but a Cat instead of a resonator
You could go less diameter piping if you wanted and have fewer mufflers but I wouldn’t go down that road I’m sure if Land Rover thought they could get more out of the motor by less diameter piping they would have gone down that road
I had mine done last week after 24 hours I had to take it back to Liverpool exhaust and have the Resonator changed to a baffled muffler it was way to loud didn’t move when stomped and it got to much attention sounded mad though but reminded me of an old HQ Holden with 253 that made sound yet didn’t go anywhere changed the resonator to muffler it revs slower it picks up better and still sounds like a real V8
Food for thought ;)
