318 build problems & new direction

cudaracer said

No I don't. I assume that would be 1-7/8" tubes? I actually have Dakota manifolds. When I select those, I lose a lot of hp, like over 40. But most people run headers, so I just base lined it with headers for reference, and then know that I am leaving plenty of power on the table.

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If you don't see over six grand very often stay with the small diameter header.
It will have better low end torque. Big tube headers are great if you are running mostly high(4500 to 8500)rpm but are generally a waste on the street. been there,done that, got the shirt.

If you're building a badass big cam high revving motor, go with big tubes....and if you have the big headers already, that's a perfect excuse to build that kind of motor for it...Most people oversize their headers because they believe bigger is better. While your peak HP number may be down with the smaller headers, you'll actually make more usable power.