I have to chime in.
WIth a 1.5" durso with my reduction down to 1.25" I had my AMPMASTER almost fully open and it handled it. It didn't even strain with a MAK4. When I was pushin it with the AM3K it was literally shaking from the velocity of the water passing through it. And I mean shaking. But with my MAK4 it was whisper quiet and never flinched. Fully open, full throttle, balls to the wall. I didn't need to restrict the flow of the MAK at all.
Do a search for my plumbing test and you will see the flow I was getting.
Something is not computing there. Sorry to say.
