Gutting out the stock cats

[Poodles]

Originally Posted by cf6mech

Or it eats itself up in my case and gets sucked into turbo read $$$$$,...now running catless and the emission smell is starting to bug me,.....it really stinks for DD use with windows down .

Ouch, it's pretty rare for that to happen as the flow usually doesn't allow it to happen. Or you have one of those idiotic setups with a cat pre-turbo (what nimrod thought that up?)

[TOTO_86]

So it is better to run with high flowing cat or no cat for power gains?

[cf6mech]

Originally Posted by Poodles

Ouch, it's pretty rare for that to happen as the flow usually doesn't allow it to happen. Or you have one of those idiotic setups with a cat pre-turbo (what nimrod thought that up?)

Yes I had the stock exhaust manifold which was pre-cat,....had my suspicions but was re-assured its fine as we have XXX number of FA20's running this setup with no issues.... costly lesson for me, but also an excuse to upgrade.

[troek]

you had a turbo on your stock exhaust manifold?

[LBC Por Siempre]

Not to mention recover all that platinum even if it is all gummed up from driving.it around. I'm keepinging it.

[NickFRS]

Originally Posted by ML

Glad someone else did it also! Sounds better then I thought. Nameless track pipe?

Originally Posted by Anorexic 86

In for dyno results...

I remember reading about Perrin doing this but they replaced the header cat with a straight pipe like you did on the front pipe. Can't find that thread at the moment.

Also... won't that inner lip cause some flow issues? Maybe grind or pry it out?

This one...

I went and bought a dermal to modify the lip there. Unfortunately all the breakers in my garage blew so I have no power till Wednesday. I did paint everything sunday though!

[NickFRS]

This is from the Perrin Blog. All Credit goes to PERRIN.



This was the first time we had tested our headers on the dyno. Based on the things we know about the car and some of its variables, we knew it would be key to do this all on the same day as all the other parts. This ensures that the HP gains we saw were legit. After seeing some peoples dyno results showing huge gains of 15-20 WHP I was excited to see what we could do. We started with two designs to see where we would be for HP, then do further tweaking from there.

Continuing from earlier in the day, the car still has all the other exhaust parts we make bolted on to it. This includes our 2.5″ catback exhaust, catless 2.5″ front pipe and 2.5″ Overpipe and NO ECU tuning.

A simple test that I am surprised no other vendors have done is take the stock header and remove the car. The stock header is built pretty good, as its a tri-y design or a 4-2-1 design. The stock header primaries are 1.625″ and the secondaries are 1.75″. So this is good as it matches the stock exhaust ports and matches what some header calculators say it should be.

One of the flaws I see is with two bends where they merge almost into each other. You can see this on Cylinder #1 and 2 above. The other flaw I see is the cat. Its not a high flow metallic core, but the standard ceramic brick which for sure will cause some restriction. Removing the cat to free up some airflow is a very simple way to see how a properly built 4-2-1 header might perform.

You can see that there are places it gains HP. Overall the HP gains were not huge, but the ECU really liked the header with no cat. We see evidence of this because the HP and TQ was more consistent run to run. Even though the WHP gained wasn’t much, but you can see how at higher RPM’s the header starts to do pick up some HP. Driving on this for a week or two I also found the same thing in that the engine was smoother and more consistent with a little more top end power. So no cat and only 3 HP

[ML]

Originally Posted by NickFRS

Glad someone else did it also! Sounds better then I thought. Nameless track pipe?

Custom made!

[NickFRS]

Originally Posted by TOTO_86

So it is better to run with high flowing cat or no cat for power gains?

A cat is a cat. High flow or OEM. Either is a restriction. People run high flow so they don't get a CEL. If you get a spacer or tune you don't get a CEL while running no cat in the header.

P.s this isn't a debate about highflow cats. that's a subject that has been flamed elsewhere in the forum.

[Kodename47]

This is mine due to go on tomorrow, will see how it fares with the S/C:

[charged86]

Originally Posted by Opposed

You will most likely lose or not gain any power. Your better off with a straight through same diameter pipe. The hollow cat will disrupt the exhaust flow and scavaging effect.

^this and it will sound like poo on a dirty stick

[ML]

Originally Posted by charged86

^this and it will sound like poo on a dirty stick

no, not really

[utekineir]

Anyone tuned for deleting the cat yet?

Comparing the untuned perrin result against untuned borla result (drift office thread) has me wondering what's left on the table.

[NickFRS]

Got my deleted items running today. Sounds fucking awesome! Car was dropped off at the tuner. Waiting for results.