"Headers", or exhaust manifolds? Rams' horn manifolds are sufficient for any speed a street engine is likely to run. Tubular steel headers don't really do anything beyond increasing under hood temperature and noise, and melting spark plug wires. There are a couple of ways to handle steering box interference-- - - -Either space the box away from the frame rail a couple of inches, or use a driver's side exhaust manifold for a 55/56 passenger car 265 engine that has the outlet toward the front of the manifold. Some late 1970's 305's used a set of manifolds with the outlet back by the firewall that will also provide sufficient steering box clearance.

Unless you're planning to run the engine above 5K RPM consistently and use a radical camshaft and modified cylinder heads, there won't a measurable gain in HP and torque with rams' horns over manifolds with the outlet away from center. I ran the rear-outlet 305 manifolds on round track 350 engines that dyno'ed at 300+ HP and 6K+ RPM.
Jerry

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