Inliners International Forums General Discussion Engines 250, should I switch to a 292 exhaust manifold?

Definitely better, 56% more area, will last 20 years if well coated. Run the larger pipe as far back as you can.

Also possible: a fabricated header made from sections of Schedule 40 weld ells, not as efficient as an actual tube header but extremely durable. Downside: $$$, difficult to make.