You'll sell a couple but not many.... Unless you feel like dropping the price way down, youll sell less.
I have made and sold 2.5" t304 and 3" t316 stainless thick mild steel flange testpipes and made enough to cover my buy in of SS stock (sill got 3.5 10' sticks of 2.5" t304 though
and a t316 3" on the shelf for my ka-t when it ever goes together), materials and a little bit extra, over the period of say a year. Mine also included all grade 8 hardware and gaskets and was at the time when only PDM-Racing was offering theirs, and no one else. It was also the only 3" on the market, and 20 or so less then pdm for the 2.5"...
Its not a very lucritive part to sell... Why would you want to invest in making a pipe then paying for the coating costs when 3" SS ones are available readilly and at a decent price from a few places.
Also the secondary o2 sensor is pre secondary cat / hollow shell, thus has no bearing on the test pipe...
Just something to think about before you go investing alot of time and money into it.... From someone who has.
Now if you are talking about making a downpipe / precat replacement then it is also a waste as I see it, as the stock manifold is still a bottle neck. One should get a real header instead of going that route as well...
