making a hx40 manifold what size id runner

[3kgt2nv]

Im making a manifold to give me a better turbo fitment and was wondering what size 1d runners would be good. this is on a 9:1 comp 2l with unported head as of now.

A lot of the aftermarket seem to be 1 5/8ths and i was wondering if that was the best size?

I will be posting pics of work as it progresses

 

[dees75z]

1.5" sch 10 is good man. Look up ace stainless on here. Good luck