im getting a new exhaust system on my 1000Copupe with A14, its only got stock exhaust manifold but probably get extractors on later, along with cam and carbs.

what is the best bore for piping for this, im thinking probably 2" system with a luky muffler. or would 2.25" be better since it will be press bent not mandrel bent...

what are you planning on doing to the motor? What extractors/cam/carbs? If your building a racecar with twin sidedrafts, Uber cam and 4-1 extractors then a 2" will be more than enough in my opinion but if its going to be a daily driver get something smaller to fit or maybe go to a performance zorst dealer like powerflow or something and ask them to work out a nice system.

i ran a 2" Zorst on my A14 coupe, it was great single lukey muffler with a bit of a gurgle on down gearing. i love it.

What is a zorst?

Zorst - Defined in the Datsun owner dictionary, as an uncommonly used noun for an A series engines way to release combusted materials, commonly known in the english language as an exhaust

Ok thanks sorry not familar with the wording over there yet I am working on it

Most of it's Australian. Even I have trouble with it sometimes

i run a 4 1/2" 'zorst' on my car, with 3" system :) and its a rotary. even though its broken atm.

i've got 2 1/2 inch mandrel bent exhaust on an a12 it works fine.

if you get extractors put on.
don't get hitech ones they rub on the bellhousing

i'm running a 2 inch on my rally car but i'm soon to upgrade to a 2 1/2 inch as i have heard from another with a 1200 rally car that he noticed an improvement going from 2 1/4 to 2 1/2. His a12 is out to about 1600cc though. This is all press bent, so probably a mandrel bent 2 1/4 would be fine but probably more expensive.