I've just been reading about some different headers but has anyone confirmed the size of the primaries on the obx's? I've seen ppl say they are 1 5/8" and others say 1 3/4"... I know they have 2.5" collectors but just wondering on the primary size.

 

i think theyre 1 5/8 but not positive. the 2.5" collectors is what turned me away from them though

 

I was just wondering if anyone had ever measured them... One of these days ima get some new headers and redo my whole exhaust I was just wonderin

 

https://www.performancetrucks.net/fo...d.php?t=450962
this thread was literally right under this one, read it..

 

Very true.

Regardless, I did not use a tape measure or a wooden ruler...Before install, I took measurements with a Mitutoyo Vernier Caliper. (like pictured below)
http://www.amazon.com/Mitutoyo-530-3...859003&sr=1-15

My Ebay header's primary tubes measured 1-5/8" inside diameter...regardless of what they advertised them as being. (I personally have no issue with that). As stated above, the collectors are 2.5", and they merge into a 3"+ collector where they join the stock, or stock style, aftermarket catback.

Knowing my engine (longblock and it's internals) will remain 100% stock, forever, I also knew that 1-5/8" primary/2.5" collector headers would be plenty enough for my intended usage, which is a daily driver that hauls/tows occasionally...yet can also haul *** if need be.