[Xplantdad]

Originally Posted by JMB

It's not as critical which tube is left/right/top/bottom because they will scavenge the same. What is more critical is the overall length based on desired RPM range, the primary tube diameter, using a stepped primary vs one diameter and then a good quality merge collector.

Equally important is ensuring ground clearance and ability to get the headers in and out without having to completely jack up the motor and also being able to change spark plugs.

The you must build a proper exhaust system to benefit from all of your hard work!

Here are my hand built triple stepped 1-7/8" to 2" to 2-1/8" true equal length primaries (+/- 1/16") 27" long with 4" diameter merge collectors and 4" exhaust system that I fabricated for my 700+RWHP NA LS7 Z06 crate motor in my '88 Monte Carlo SS.

Very nice!