Here's a different opinion-
"Everyone tested the merge collectors for the Engines Masters contest, THey dont work, it is a big waste of money. You might find 3 or 5 HP somewhere in the power curve, but no where near what they cost per HP/ dollar.Some times it was even worse than regular collectors.
The 4-2 one design has some good merrits though."
JOE SHERRMAN RACING ENGINES
Versus-
"Thanks for your experience, Joe!
Hooker used to offer a 4-2-1 collector some time back. I purchased a set and installed them on my Hooker Super Comps. Flowmaster had them as well, but the Hookers were a much smoother design.
A person has to be careful with the 4-2-1 collectors. The Ford firing order is 1-3-7-2-6-5-4-8 and you don't want successive firings going into the same merge. For example, you don't want 1-3 going into the same merge, as it can cause a 'traffic jam'. You want to pair the impulses as far apart as possible. On the passenger bank, maybe 1-2 paired and 3-4 paired.
Of course 'ideal' pairings aren't always possible with 4-2-1 collectors, but you can usually rotate the collector to make the pairings as ideal as possible. Mine are turned two different ways on my car.
I like the Hookers, but don't think they are made anymore. Nice, smooth transitions".
Hum,.....