Im wondering what size pipe we use for the header pipe. Im thinking its sch. 40 1 1/4" which has a 1.66 OD. Can anyone confirm this?

 

im using 1.5" fwiw

 

is that the OD?

Hey just got the miata to pass emissions. i finally get to replace my 01/2008 tabs.

 

1.5" SCH10 (1.9 OD) is what everyone uses.

I considered making a 1.25" to see the spool vs peak power difference between the two. You may need to use one of strainghlinespecialties' transitioned head flanges to fit a 1.25" pipe though, since I don't think 1.66" will stretch enough to match the oval port.

 

Nice dude! Thats no small feat with a standalone ECU!

 

I'll be building one this winter with 1.25.

 

I have enough 1.250" sch.40 mild weld els to make a mani some one could talk me out of,Not a formal offer of sale just point of interest.if a reader of this thread wants them come and get them orsend me some shipping love and you can have them.
-G-