) and they do concur with the diameters on
manifolds that I have used in the past from BTB/SBD. The issue this time is that I am making my own manifold and the economic way for me to do it is to use 316 stainless hygienic tubing................the problem is that I can only then choose between 1/2" increments.
For the primaries 1.5" is too small, and the next option up is 2".
The question is....will using 2" primaries AND secondaries lose me a lot of mid range torque?? It would certainly make creating a nice 4-2-1 manifold easier as I will have to buy less pipe!! The final pipe will be 2.5", which apparently is correct for 200-220hp, and usefully fits the Caterham R500 carbon silencer that I aquired.