65OldsDelta88SuperRocket

I purchased a reproduction starfire exhaust manifold for the drivers side of my 65 delta 88.

Today I removed the drivers side manifold in preparation for the new one.

My question is on my big 425ci 7.0l motor....

Can I run 3" pipes on both sides to 3" mufflers or is that too much?

Or should I stick with 2.5" piping?

Thanks experts!

MDchanic

How fast do you plan to rev it?

I can't imagine needing more than 2½" for a stock motor that shifts at about 4,500 RPM, especially with manifolds.

- Eric

rocketraider

2-1/2" is gracious plenty for that engine in that car. 2-1/4" might do fine since you're opening up to dual exhaust.

Bigger than 2-1/2" is a waste of time and money and will probably hurt the car's performance more than it helps. It might help top end, but would kill low speed torque.