Real talk: exhaust manifolds on 360 Dart

Here's a manifold/header shootout on a 300+hp 360 the difference was 1-5hp depending what rpm.

https://www.motortrend.com/how-to/mopp-0307-installing-exhaust-headers-into-300hp-crate-engine/

Horsepower
RPM318360340SHT1 58tti1 34
2500186185187189187189187
3000223223225226228228226
3500269271272276280281279
4000299301306307314318312
4500311313315321319326321
4600311314315320317327319
5000303304308315312316311
5400281291289295282296289
Wish they'd done the 64-66 273 manifolds too. Just to see if they're really that bad