Changing to Headers
 

Standard Porsche 911 coupe 1975 2.7Litre

I am removing the standard exhuast system and installing a pair of headers complete with a dual inlet/single outlet muffler.

What size are most suitable for this engine the 1 5/8" or the 1 1/2" ??

Niall

If the engine is stock, 1.5" would be the best size. If you are in Ireland, though, aren't you going to miss the heating and defrost function of the heat exchangers?

TT

I am preparing the car for track day and classic rally use. I dont think the heating system will be required.

FWIW, I used 1 5/8" on my 2.7. That was the conventional wisdom at the time. They seemed to work great (no before/after dyno testing).