Seems as though O.S. is going to offer a engine/pipe combo for the 3-port model. This following was taken from http://www.os-engines.co.jp/tz/english/12tz_3.htm :

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MAX-12TZ(P)-T3 R52 COMBO
Fits for exhaust to Right side. Ex. Kyosho’s FW-05 series.

11H Slide carburetor / Pilot Shaft
P6 Glow plug, Exhaust seal ring,
Tuned pipe (T-1040SC R52),
Exhaust manifold (M1011SC) included.

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MAX-12TZ(P)-T3 L52 COMBO
Fits for exhaust to Left side. Ex. Kyosho’s V-one-R series, Mugen’s MTX-3 series.

11H Slide carburetor / Pilot Shaft
P6 Glow plug, Exhaust seal ring,
Tuned pipe (T-1040SC L52),
Exhaust manifold (M1001SC) included.

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Personally, I'm going to go with the Mugen Seiki 1/10 on-road pipe (I have a MTX-3 Prospec). I have Mugen's 1/10 off-road pipe mounted to my O.S. .12TR in my RC10GT and I am completely satisfied. I see no reason not to try the on-road version.