[MAGAUSA]

Forget headers. Always wanted them and will probably get them eventually but for the sake of this post, haven't seen where high flow cats alone have been installed. Can't see where LT headers themselves would make the hp gains. LTs are always mated with no cats or HF cats. The stock manifolds are not awful. They look pretty good for stock actually. I'm thinking HF cats with a tune would yield similar gains to headers/HF or no cats and a tune.

btw I broke down and ordered the Borla S exhaust after all my complaining over the price, which is very high for what it is.

[EFI Tuning]

I ran with the CA delete pipes for quite a while (deleted the primary cats). Don't waste your time messing with the stock manifolds and other cat permutations. You won't achieve anywhere near the gains you will with headers.

Tim

[MAGAUSA]

What's a layman's reason for this in an otherwise stock setup? Can't be the scavenging is it? Cats are restrictive. Free them up with HF cats and with a tune there must be decent. gains

[marknagy13]

Headers have shown to provide gains regardless of the cats, but I'd do it mostly for the sound anyways

[BradfordCamaro]

Originally Posted by EFI Tuning

Don't waste your time messing with the stock manifolds and other cat permutations.
Tim

Holy S**T Dude. Ease up on the College lingo

[EFI Tuning]

Too many letters all at once?

[BradfordCamaro]

Originally Posted by EFI Tuning

Too many letters all at once?

and the Smirnoff.....



...Easter sale?

[TJay74]

Scavenging, header tube length, tube size all factor into the fact that a set of headers with HF cats will always make more power than the stock manifolds even with no cats or even HF cats. To be honest the stock cats are already considered HF cats due to the application they are on.

[Lemosine]

Instead of gutting them get a straight pipe welded. But you wont see gains like long tubes by just doing that. Easy was to break it down is like the guys said above, Scavenging.

[oldman]

CA test pipes and secondary stock cats yield a handfull of HP IMO, the stock 2nd cats are quite big internally and are 3" in and out, with an even bigger internal volume of about 4.5" round equivalence. Plus they are near straight to the flow. Long story short, no way on a stock or bolt on engine they are going to lose much compared to straight pipe or high flow cats. This is the same exhaust as the ZL1 after all.

So, if you run CA pipes and either run the 02 behind the secondary cats or turn them off. you should have a small gain. Going to full high flow secondary cats will yield nothing measurable upto and past full bolt ons.


I'd go with JBA or other brand sub $1000 headers and $300 cats. if you are bucks down. For me I went with Kooks and straight pipe, I already had 3" cat that I welded in. I was going to just weld in the stock secondary cats but I alread the 3" from my supercharged civic and Volvo projects.. There is a brand of header out now (forget that just bolts to the secondary cats and is cheap....problem solved.

[Fraxum]

Originally Posted by MAGAUSA

What's a layman's reason for this in an otherwise stock setup? Can't be the scavenging is it? Cats are restrictive. Free them up with HF cats and with a tune there must be decent. gains

The reason is the stock cats flow pretty well. This is part of the reason we do not see a large gain with LTs IMO

[hogwild87]

What in permutations!?

[BradfordCamaro]

Originally Posted by hogwild87

What is permutations!?

When you bring the girl back from the bar...and your gun goes of before second base..... I think....

[Tomiboy]

Originally Posted by BradfordCamaro

When you bring the girl back from the bar...and your gun goes of before second base..... I think....