Early Production (1975–1979)

1975–1979 model-year 930 Turbos came from the factory with a single exhaust outlet muffler.

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Change to Dual Outlets (1980 onward – ROW)

Starting with 1980 model-year “Rest of World” (ROW = Europe and most non-US markets) cars, Porsche introduced a dual exhaust outlet muffler (a "shotgun" configuration on the left side of the bumper, with double horizontal outlet) as standard.

Note: for 1983 MY there was a revised design for the wastegate outlet, but this is outside of scope.

During the 1984–1989 period Porsche standardized the "shotgun" exhaust outlet worldwide (including U.S., Japan, Switzerland, etc.)

Note: It must be said that from MY 1980 through MY 1985 (inclusive) Porsche withdrew the 930 Turbo from the U.S. market because the existing engine and emissions systems no longer complied with U.S. regulations. The 930 Turbo was re-introduced to the U.S. in 1986 with updated emissions controls (catalytic converter, oxygen sensors, and LE-Jetronic management), making it compliant with U.S. standards.

930 Turbo WLS exhaust setup

For the Porsche 930 Turbo with WLS (Werksleistungssteigerung) 330 hp engine kit, the exhaust layout was factory "shotgun" dual outlets with larger-diameter tips than standard 930 in most cases, integrated with the WLS turbo, headers, and higher-flow muffler. There was no factory WLS with a single exhaust outlet, as far as we know.

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The four tailpipes (two left, two right) was featured on 1989 Porsche 930 Turbo S (M637) – ROW. This was part of the "Turbo S package", which included:

• Higher output (~330 hp)
• Larger turbo & intercooler
• Special exhaust and muffler

This was produced in very small numbers (~55 units + 53 Turbo LE for UK, all Coupés) and it is the only universally accepted factory quad-exhaust 930 Porsche, albeit some similar Sonderwunsch (Special Wishes) modifications might had been performed as well (e.g. on Flachbau specs cars).

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Quick reference table

Model	Exhaust outlet setup
930 3.0 (1975–79)	Single outlet
930 3.3 (1980–83 ROW)	Dual (L + R)
930 3.3 (1984–88)	Dual (L+L)
930 Turbo S (1989, M637)	Quad (L+L / R+R)