Exhaust system with plural silencing units

Claim 1

AN EXHAUST SYSTEM FOR AN INTERNAL COMBUSTION ENGINE COMPRISING AN ELONGATED EXHAUST PIPE HAVING AN INLET END AND AN OUTLET END, FIRST AND SECOND SILENCING UNITS POSITIONED ALONG THE LENGTH OF SAID EXHAUST PIPE, SAID FIRST SILENCING UNIT COMPRISING AN OUTER PIPE, A REDUCED DIAMETER INLET BUSHING MEANS FORMED AT ONE END OF SAID OUTER PIPE AND REDUCED DIAMETER OUTLET BUSHING MEANS FORMED AT THE OTHER END OF SAID OUTER PIPE, SAID OUTER PIPE HAVING A FIRST REDUCED DIAMETER PORTION FORMED ADJACENT TO SAID INLET BUSHING MEANS, A FIRST INNER PIPE EXTENDING FROM SAID INLET BUSHING MEANS TO SAID FIRST REDUCED DIAMETER PORTION AND SUPPORTED THEREBY FOR DEFINING A FIRST SILENCING CHAMBER BETWEEN SAID FIRST INNER PIPE AND THE PORTION OF THE OUTER PIPE BETWEEN SAID FIRST INNER PIPE AND THE PORTION OF THE OUTER PIPE BETWEEN SAID INLET BUSHING MEANS AND SAID FIRST REDUCED DIAMETER PORTION, A SECOND REDUCED DIAMETER PORTION FORMED IN SAID OUTER PIPE ADJACENT TO SAID OUTLET BUSHING MEANS, A SECOND INNER PIPE EXTENDING BETWEEN SAID OUTLET BUSHING MEANS AND SAID SECOND REDUCED DIAMETER PORTION AND SUPPORTED THEREBY FOR DEFINING A SECOND SILENCING CHAMBER BETWEEN SAID SECOND INNER PIPE AND THE PORTION OF SAID OUTER PIPE BETWEEN SAID SECOND REDUCED DIAMETER PORTION SAND SAID OUTLET BUSHING MEANS, A PLURALITY OF LONGITUDINALLY SPACED OPENINGS IN SAID FIRST INNER PIPE WHEREBY SAID FIRST SILENCING CHAMBER FUNCTIONS AS A SPIT CHAMBER AND A PLURALITY OF PERFORATIONS IN SAID SECOND INNER PIPE WHEREBY SAID SECOND SILENCING CHAMBER FUNCTIONS AS A SPIT CHAMBER, SAID SECOND SILENCING UNIT COMPRISING AN ELONGATED TUBULAR OUTER PIPE, A REDUCED DIAMETER INLET BUSHING AT ONE END OF SAID OUTER PIPE AND A REDUCED DIAMETER OUTLET BUSHING AT THE OTHER END OF SAID OUTER PIPE, A REDUCED DIAMETER PORTION FORMED IN SAID OUTER PIPE ADJACENT ONE OF SAID