Is that...are those really...

When you're working on your own exhaust you'll care more than when you're on the clock at a job that pays you minimum wage. You'll make sure joints are straight, and everything is smooth as possible while him.. he just has to make it work.

Your manifold is a perfect example.

got the pusha inspired Lady revving relay!
https://www.miataturbo.net/attachmen...ine=1339532601

https://www.miataturbo.net/attachmen...ine=1340224076

I found some 70 x 1.5 mm ss elbows and pipe so I can start to fab the cutout/downpipe.

As pointed out where to put the wideband?

Will there be enough flow through the stock exhaust when the cutout is open to give a true reading on the wideband?
If yes then I could place the wideband somewhere close to the stock cat.

Who knows, there could even be reverse flow through the stock exhaust due to venturi vacuum effect when the cut out is open? Probably not though if the cut out pipe is long enough to create some back pressure.

The wideband could be placed at the y which is not ideal as WB should be a min of 12 inches and not exposed to more than 900 deg F? https://www.miataturbo.net/attachmen...ine=1340224076

For now I guess I will add 4 bungs, 2 at the y, 1 before the cat and 1 at towards the end of the cutout and push the engineering burden onto the guy testing it....:giggle:

Wasn't there a thread few months ago with clean air going back and influencing the wideband reading? I hope that doesnt happen for you.

Yeah I dont think that would be the most ideal setup. Youre going to want it further down from the turbo IMO, or at least weld in a heat shield. I'm not sure how well they work, but I've seen setups that have a curved chunk of metal, maybe 5/32" or more, welded right in front of the O2 sensor.

I really think the best idea would probably have it at the elbow where the downpipe curves to go to the back of the car. Just have the cutout continue the downpipe's path

that looks like a horrible downpipe design if you go through with it. I hope you come up with something better otherwise just stick to the "traditional" routing

what is the traditional routing when a cut out is placed between the turbo outlet and stock downpipe connection?

Cutout is placed right before the cat..or where the cat would be, wideband goes about a foot before that.

is there enough space under there to fit the turbo? it seems like it'd be awkward like that because it's so low to the ground.

Good question!

The turbo flange sits 3.75" bellow the manifold center line which is similar to other low mount setups. Available Products

From my measurements the turbo flange could be 6" and more bellow center and still be OK for drain line routing. I will fit this soon and post pictures.