Marine exhaust system

1. An exhaust system comprising:

a muffler including a body with an internal volume, a first baffle and a second baffle located within the internal volume;

a first manifold including a bend located within the internal volume;

a second manifold including a bend located within the internal volume; and

a balance tube including an oxygen sensor, the balance tube in fluid communication with the first manifold and the second manifold

wherein the first manifold, the second manifold or the first and second manifolds extend through at least one first opening in the first baffle and at least one second opening in the second baffle.

2. The exhaust system of claim 1 , wherein the oxygen sensor is configured to measure an exhaust gas concentration of oxygen in the first manifold and the second manifold.

3. The exhaust system of claim 1 , wherein the first baffle and the second baffle divide the internal volume into a first chamber, a second chamber, and a third chamber.

4. The exhaust system of claim 3 , wherein the first manifold extends into the first chamber of the muffler and extends through the muffler to the third chamber.

5. The exhaust system of claim 3 , wherein the second manifold extends into the third chamber of the muffler and extends through the muffler to the first chamber.

6. The exhaust system of claim 1 , wherein each of the first baffle and the second baffle includes perforations to allow exhaust gas to flow through the first baffle and the second baffle.

7. The exhaust system of claim 1 , wherein the muffler includes mounting brackets that are configured to attach the muffler to a cylinder head of an internal combustion engine such that a muffler load is in an axial direction.

8. The exhaust system of claim 1 , further comprising:

a heat shield configured to shield the balance tube from heat generated from an internal combustion engine.

9. The exhaust system of claim 1 , wherein the muffler includes at least one drain hole configured for draining water within the muffler.

10. The exhaust system of claim 9 , wherein the at least one drain hole is located between the first and second baffles and wherein each of the first and second baffles includes channels configured for draining water across the first and second baffles.

11. An internal combustion engine system comprising:

an internal combustion engine including a first cylinder bank on a first side of the internal combustion engine and a second cylinder bank on a second side of the internal combustion engine;

a muffler including a body with an internal volume, a first baffle and a second baffle located within the internal volume, wherein the first baffle and the second baffle divide the internal volume into a first chamber, a second chamber, and a third chamber;

a first manifold including a bend located within the internal volume;

a second manifold including a bend located within the internal volume;

a balance tube including an oxygen sensor, the balance tube in fluid communication with the first manifold and second manifold; and

an exhaust pipe;

wherein the first manifold extends into the first chamber of the muffler and extends through the muffler to the third chamber.

12. The internal combustion engine system of claim 11 , wherein the first manifold extends from the first bank through a first side of the muffler and the second manifold extends from the second bank through a second side of the muffler.

13. The internal combustion engine system of claim 11 , wherein the muffler further comprises mounting brackets on the top of the muffler that secure the muffler to a cylinder head of the internal combustion engine, supporting the muffler in an axial direction.

14. The internal combustion engine system of claim 11 , wherein the oxygen sensor is configured to measure an exhaust gas concentration of oxygen in the first manifold and the second manifold.

15. The internal combustion engine system of claim 11 , further comprising a heat shield configured to shield the balance tube from heat generated from the internal combustion engine.

16. A method of manufacturing an exhaust system for an internal combustion engine system, the method comprising:

forming a muffler including a body with an internal volume, a first baffle and a second baffle located within the internal volume;

forming a first manifold with at least one first bend;

joining the first manifold to the muffler, wherein the at least one first bend is located in the internal volume and the first manifold extends through a first opening in the first baffle and a second opening in the second baffle;

forming a second manifold with at least one second bend;

joining the second manifold to the muffler, wherein the at least one second bend is located in the internal volume;

forming a balance tube;

joining the balance tube to the first manifold and the second manifold such that the balance tube is in fluid communication with the first manifold and the second manifold;

inserting an oxygen sensor into the balance tube;

forming an exhaust pipe; and

joining the exhaust pipe to the muffler.