Because rumbles register on my radar.

If you concerned about effecting you warantee then don't get headers or mess with the cats or o2 sensor positions. The dealer will spot that in about 10 seconds, and as soon as you do any of that your putting your engine warante at risk.

To an extent yes. I think they can more easily deny claims and deny many more things if the ECU is flashed versus just replacing the header.

with a flash

A. they have got to find it, unlikely unless the pull your ROM and Analise the actual hex code they wont know, as the calid in techstream will be the same as a stock calid for a tuned ROM.

B. If you have the ability to flash back to 100% stock ROM then their is sod all chance of them finding anything and even if they find the mythical flash counter (which I have yet to find in techstream) then all they have is a stock ROM and no proof anything else was in there.

Unlike hardware mods which are in plain sight and difficult/time consuming to swap out for service.

I already own the header and not spending $500+ on a tune. I'll be using a catalytic converter of some sort to get it right.

I've used the anti-fouler trick a few times before on different vehicles with much success. $3 fixes are my favorite.

Having a bung welded after your second cat, extending the wiring and hoping it works seems much, much more difficult/expensive.

See post #28 and #30

Like I said, this seems like the much more difficult and expensive route. I could have this fixed in <5 minutes with a $3 part.

But is your fix messing up your a/f ratio being it's not a true cat?

No? Only the first O2 sensor is used for that making these adjustments. Taking readings from the second O2 sensor after a cat to try to adjust A/F doesn't even make sense.

The second O2 sensor is literally only there to ensure your cat is working, this reading is not used for any engine management purposes.

Now that I think about it, that makes sense. Thx bud

Though, I already bought the bung and o2 sensor extension cable. So as long as the welding the bung is cheap that will be my cheapest route at this point.

Let us know how that goes, I'm curious if the secondary cat is enough(I'm thinking the primary may work better as it's operating at a better temperature). You may also run into the problem that you can't get the second O2 sensor hot enough in that section of pipe but it's worth a shot.

As far as getting a bung welded in it's usually $10-20 depending on if on the car or not.

Another member has done this with success for 5k+ miles

Lol finally....

Btw, there will be a delay since you are placing it further back. Just because some moron done it for 5K miles doesn't mean he knows what he is doing.