hi turbomar
i bought a pair of the obx for 180 shipped, around xmas on make an offer on ebay w vendor.
watch their sales.
any how we cut off the front tubes and welded in metal to fill the log.
put on the o2 bungs, and cut the tube to the outlet flange and then my welder went to prison. his house repo'ed and my jigs were lost in his transition to federal housing. for awhile,... modified weapons.
so here i sit, needing the jigs as my stock headers were long since put back on the car.
turbomar,... can you help?. i have no interest in making more, only finishing mine.
a loan, a lease , a rent, i'll swear on my canadian daughters head i wont duplicate the jig or make more sets.
i'd swear on the wifes head but she's dead and gone

to the questions on size
primaries are about 1.5- 1.625" and accept stock gaskets.
the main log is 2.0- 2.1"
outlet size of the header flange is 1.75" but it can be enlarged to 2.0", the size of the downpipe fm needswings or the inlet of the cats.
the header flange thickness is .375"
as you can see the outside of the obx is very nice and the inside somewhat rough and needs some cleanup inside of dross, or whatever the welding debris is called
the hardest part of the stock header removal was the overtightened (by dealer) factory copper nuts to the head studs. they will round easily and a six point socket w wobbles and u joints worked the best for us.
space is tight but when you undo the motormounts it just takes patience.