lambda/o2 sensor relocate or not with new downpipes?

[stapo69]

I have a set of Labree split-mouth downpipes on there way from the states, they come with hi-flow main cats, but these bolt in on flanges so will be having some decat pipes made up.

My question is I have a 1998 S4 with just the 2 front O2 sensors, when fitting these new downpipes will I have to relocate these to the sensor bungs near the rear cats, or will they be fine in the front positions at the top of the downpipes?

Read various different things and getting confused, some moved, some left, some gapped with spark plug defoulers. What do I do?

Thanks in advance for all your wise words!

[grizz]

Are they the ones that have 2 small pipes from the turbo flange to the cat ??

[S4]

I see them here.... http://www.labreemotorsports.com/products_vw.html what are they like?


Darren

[stapo69]

Yeah those are the ones, got them for $400 off ebay so a bit of a bargain as they're nearer $1600 new. Read up quite a bit, seem to love em over on audizine. Seem to work well, gonna be better than the standard ones for sure.



Some more info here: http://www.tantrumwerks.com/html/splitdp.html

Thoughts on whether the lambda sensors need moving anyone?

[grizz]

Looks like they've got the lambda boss in the right place , I don't think they will flow very well ....

[stapo69]

So I'm fine leaving the lambdas in the downpipes and just bunging the lower ones? Just thinking when people de cat there standard downpipes I noticed in the diy write ups they tend to move the probes down to after the main cats.

Quite a few people running these on KO4'd cars with great results, mostly in the states though, they don't look like they'd work well, but they do apparently, less disruption in the air flow having the pipes seperate, explains in the link above, a lot of jap cars run similar set up. This is a more expensive option so not so many use them.

The guy I bought them off ran them with KO4s and said the spool up was pretty much instant, but then he totalled his car so sold what was left of it!

[stapo69]

http://www.tantrumwerks.com/html/dpdynos.html

30whp gain on stock car, 75whp with Milltek 3" catback and MTM on chip, on crap 91 octane US fuel