Comparison of exhaust note between a 1970 T/A & 1978 Y-82 T/A.
1970 has Ram Air IV Manifolds with 2.5 inch opening going into a pypes 2.5" down pipe into a Flow Master American Thunder Series exhaust mandrel bent with H-Pipe into Texas TA mufflers and 2.5 inch tailpipes.
1978 Ta has Dougs long tube headers with 1 7/8th inch primary into 3 inch collector with a Pypes 2.5 inch mandrel bent exhaust and x-pipe. Also has Texas TA mufflers.
The 78’ SE has a 406 with 6X#4 heads. The camshaft is a comp cam XE274H. Specs are flat tappet 274/286,230/236,.488/.491, 110LSA. Rockers a roller tip @ 1.5.
The ’70 has a 433 RAIV. The camshaft is a Butler custom grind. Specs are hydraulic roller 282/288,230/236,561/573, 112LSA. Roller rockers @ 1.65.
Here is the comparison video with both cars:
https://www.youtube.com/watch?v=DcVQ_recmz0
Here is the 1978 by itself to give you an idea of how the car sounds by itself:
https://www.youtube.com/watch?v=uoPq4dDVyW8
I would think the car with the long tube headers would be louder even with the X-pipe. Evidently, not the case.