Does anyone know the diameter of the intercooler internal hose section on the sti (p1)

 

The connecting pipe diameter, if thats what you mean is the same as a standard Intercooler.
I've a P1 Intercooler on mine and it fits exactly the same as the original MY99 one that came off, the internal air chamber is bigger and hence cooling efficiency is greater on the P1 STi5/6's IIRC

John

 

Thanks for that mega stream, I need to know the measurment in MM if anyone knows.