Working Silent Choice exhaust system for Mercruiser 454. I think it works with a small block exhaust, too. Was on a 88 Galaxy 26' boat with a 330HP 454/Bravo 1.

Used, can text you a video I took of it working before I removed it.

Contains the 2 y-pipes, air actuators, air pump, outlets with rear flappers and switch. Hook up power and ground wires and it's working. I would replace the plastic tubing, and one connector screw is missing on one of the air actuators. Both are readily available. Asking $750

Click image for larger version. 

Name:	P1020113.jpg 
Views:	17 
Size:	317.3 KB 
ID:	457715Click image for larger version. 

Name:	P1020114.jpg 
Views:	18 
Size:	299.3 KB 
ID:	457716Click image for larger version. 

Name:	P1020116.jpg 
Views:	21 
Size:	318.8 KB 
ID:	457717Click image for larger version. 

Name:	P1020115.jpg 
Views:	16 
Size:	323.3 KB 
ID:	457718Click image for larger version. 

Name:	P1020117.jpg 
Views:	16 
Size:	293.0 KB 
ID:	457719Click image for larger version. 

Name:	P1020119.jpg 
Views:	14 
Size:	262.9 KB 
ID:	457721Click image for larger version. 

Name:	P1020120.jpg 
Views:	12 
Size:	309.9 KB 
ID:	457722Click image for larger version. 

Name:	P1020118.jpg 
Views:	14 
Size:	294.1 KB 
ID:	457720