mtocrs1

Installed Shotgun Silencers on my 330hp 454 that has minor upgrades. Imco poweflow manifolds, Edelbrock Performer intake and performer 750 carb. After I installed the silencers I lost 200RPM. Went from 4600 to 4400. I also lost 3MPH! What gives? The boat is quieter but thats a big loss. I thought these things were supposed to flow straight through at speed. What hole should my flapper arm be in? Top? Middle? Bottom? Do they make smaller springs to allow the flappers to open easier. I thought it would be just as loud wide open but it is not. Help!!!!

AIR TIME

TAKE YOUR FINGER STICK IT UNDER THE FLAP SEE HOW IT FEELS. THEN TRY ANOTHER HOLE AND CHECK AGAIN I CAN CHECK A SET I HAVE IN THE MORING THERE THE 1ST DESIGN WITH THE HOLES IN THE FLAP NOT ON THE BOTTOM SO I'LL ADJUST TO SEE WHATS SOFTER AND GET BACK TO YOU . PS IT SOUNDS LIKE YOURS ARE NOT OPENING ALL THE WAY YOU SHOULDN'T LOOSE RPM AND SPEED THEY SAY YOU SHOULD PICK UP TQ MID RANGE. ART

Griff

The top hole allows them to open the easiest. They must really be staying closed for you to have lost anything. And yes, they do make different springs for different HP levels. You could have the wrong springs for your HP level. Call Drew Marine. They're Cust service is pretty good and they'll probably just send you some new springs.

I have them on my boat. At WOT they are 3/4 open and sound like they are not even there.