Help fir Sport Muffler conversion

[Walter Mueller]

I am currently building a 1970 911 engine to a 2.5 L+ displacemnt. When finished I am considering the common sport muffler conversion from a used stock muffler, however I would like to tone down the noise. If I weld in 2 in O.D. exhaust outlet pieces, keeping these stubs about 1 in long, is there an insulated 2 in I.D. pipe(preferrably chrome) about 6-8 inches long that can be attached to these stubs for sound deadening? If available, what would be the maximum O.D. of these overlay pipes to prevent the license panel from getting too hot, even though the insulation within would give some heat protection? All comments are welcome.

Walt