Piggy Pipes same as Gutting PreCats?

Post by **leebske** » Sun Nov 04, 2012 7:30 pm

Hey everyone,

I've done a tone of searching and sorry if I sound stupid but I'm assuming the reference "Piggy pipes" is just the method of gutting the pre-cats?

Does anyone have a walk through picture illustration of this DIY?

Thanks a lot

Post by **RS4pete** » Mon Nov 05, 2012 12:30 am

Yep, piggie pipes refers to gutting pre cats. There was a very helpful chap who put a full write up on DIY piggies with good pics, must have been about a year ago. Have a search.

Post by **sonny** » Mon Nov 05, 2012 12:31 am

As far as im aware, Americans call precats "piggies".

Gutting the pre cats is pretty easy, by drilling out the element. Be careful not to let it fall into the main cat as this can cause damage.

Post by **sakimano** » Mon Nov 05, 2012 4:41 am

sonny wrote:As far as im aware, Americans call precats "piggies".

Gutting the pre cats is pretty easy, by drilling out the element. Be careful not to let it fall into the main cat as this can cause damage.

piggies is what Americans (and Canadians) call stock downpipes with the main cats in tact, but the precats gutted.

Piggie was Mike from vast in Detroit's nickname. Vast came up with this mod for the B5 S4 which also had a similar catalyst setup to the B6/7 S4/RS4...two per side. They named it 'piggies' after Mike.

Post by **leebske** » Mon Nov 05, 2012 5:37 am

Thanks for the clarification

Does anyone have a link to this picture guide?

Cheers

Post by **gareth_oau** » Mon Nov 05, 2012 7:06 am

hi sakamono - great bit of history there!!

mike from detroit must be quite proud that a common term in the industry is named after him.

Post by **gareth_oau** » Mon Nov 05, 2012 7:07 am

another question -

If i plan to instal hi-flow downpipes in the near future, then is it still worth doing the piggies or no?

Post by **sonny** » Mon Nov 05, 2012 12:21 pm

Fantastic bit of history indeed, well done Mike.

If you purchase milltek sports cats these already have the free flow down pipe attached (no pre cat).

If you gut the oem pre cat you you in effect have the same thing.

Both will need remapping accordingly

Oem main cat are 200cells ad pre cat is 400cell iirc

Milltek do 200 and 100 cell cats.

Post by **RS4pete** » Mon Nov 05, 2012 10:31 pm

Ok, so i've looked (really quite hard) and i cant find the DIY guide

It appears that some just drill out the pre-cat innards using a auger/ flat bladed wood bit. That seems a bit dodgy to me due to the risk of swarf getting into the main cat and messing it up. It must be easy to cut the pre-cat open and remove the innards properly then reweld.

Regarding remaps, mines been running perfect with Millteck 100 cell cats and a non res system without a remap or lamdba spacers.

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