68-70 Hi po manifolds vs quality headers

Hughes engineering also post results on their website: Two motors, stroker based on a 360 block and stroker based on factory 340 block. ALL stock iron ported and extrude honed. the 1st 360 test based 409 peak HP, 429.7 TQ with manifolds. Test 2 360 added the tti headers: 471.6 peak HP, 498 peak TQ. To note, at 2600 rpm there was a 42 hp increase and an amazing 82 ft lbs tq increase headers only.
The 340 stroker included Hughes stage II ported heads, extrude honed intake and factory 68-70 hi-po manifolds. With manifolds 447HP, 471 peak TQ. Added exact same tti headers only: 478 peak HP, 507 peak tq.