What is the benefit of a 4-into-1 merge collector over a standard collector?
A true merge collector uses a more gradual transition and often includes an internal spike. This design maintains high exhaust gas velocity and improves the "scavenging" effect—where the pulse from one cylinder helps pull the exhaust out of the next—resulting in better throttle response and more power.
Should I choose Stainless Steel or Mild Steel for my collector?
304 Stainless Steel is the premium choice for longevity and aesthetics, as it resists rust and holds a polished finish. Mild Steel is easier to weld for beginners and is a great, cost-effective choice for vehicles that aren't exposed to extreme salt or moisture.
What does the internal "merge spike" do?
The spike (or pyramid) is located in the center of the four primary pipes. It eliminates the turbulent "dead zone" where the four pipes meet, smoothing the transition into the single outlet pipe and minimizing backpressure.
How do I choose the correct inlet size for my 4-into-1 collector?
The Inlet (In) size must match the outside diameter of your header's primary pipes. For example, if you are using 1-7/8" tubing for your extractors, you must select a collector with 1-7/8" inlets. The Outlet (Out) size should match the diameter of your main exhaust system (commonly 3" or 3.5").
