Alright I need some new couplings for my car. My question is before I order them I need to know wether or not the measurements that are stated on the website are internal diameters or outside diameters? Take for example http://www.atpturbo.com/Mercha...L-STR is that a internal measurement or outside? I got 2.5" piping and want to make sure that they stuff is gonna fit before I got and order it. TIA

 

they are inner diameter, where u need to worry is with the clamps

for 2.5" piping u need the 2.75" clamps, read the desciption at the bottom, that should help.

 

I just went and bought some 2.5" hose from Napa that is actually more heavy duty than the other stuff.