V band sizing

[Keeper1343]

i am looking at running a hx35 soon and was trying to find how big the downpipe has to be. I keep reading its around 3.75 to 4" v band flange. My question is whether its that size on the outside diameter or inside diameter of the flange?

[RyanG]

Most likely outside. The issue youll have is most diesel turbos require a special clamp and flange. We send them to the machine shop to get the flanges cut off and we weld our own vbands onto them

[Xceleratetune]

Actually the inside. But if you measure it lets eighther in or out it will only be 1/4 difference. And the flanges are being sold by 1/2 so if you measure 3" from inside and 3.25 from outside then its 3".