Re: 427 FE engine, under car 'street' exhaust system?

[cycleguy55]

A pair of 2.25" tubes has more cross-sectional area than a single 3" tube (3.98 in² x 2 = 7.95 in² vs 7.07 in²).

How about building headers with paired cylinders (similar to Tri-Y headers) and run a pair of 2.25" tubes back to mufflers with dual in / dual out (quad tips) - something like the Magnaflow 11378? Alternatively, you could run dual in / single out (e.g. Magnaflow 12158, 12258, 12278) for a more period-correct appearance.

[Buzz]

.....

[AC Ventura]

Originally Posted by cycleguy55

A pair of 2.25" tubes has more cross-sectional area than a single 3" tube (3.98 in² x 2 = 7.95 in² vs 7.07 in²).

How about building headers with paired cylinders (similar to Tri-Y headers) and run a pair of 2.25" tubes back to mufflers with dual in / dual out (quad tips) - something like the Magnaflow 11378? Alternatively, you could run dual in / single out (e.g. Magnaflow 12158, 12258, 12278) for a more period-correct appearance.

Actually this might be the solution.

Each side: Two 2" down pipes = a cross sectional area of 6.284 sq in.

This area equates to a single downpipe of 2.83" diameter.

So two y headers each side, running into two dual entry mufflers. I think this is a good compromise. Thanks