If we are talking about differences between no cats and high-flow cats... there is basically no difference there at all. The only thing you lose by putting on some high-flow cats (like the ones from Bassani) is the loss of some drone and resonance. Now, there is a few HP gain when you go from the stock cats... which are very restrictive... to some high-flow cats. I'm guessing around 5 or so.

 

<div class='quotetop'>QUOTE(acadian @ March 1, 2006, 10:02 AM) Quoted post</div><div class='quotemain'>
If we are talking about differences between no cats and high-flow cats... there is basically no difference there at all. The only thing you lose by putting on some high-flow cats (like the ones from Bassani) is the loss of some drone and resonance. Now, there is a few HP gain when you go from the stock cats... which are very restrictive... to some high-flow cats. I'm guessing around 5 or so.
[/b][/quote]

That's what I was looking for, thank's everybody. What would be the difference in sound with HF cat's or no cats's!

 

Hey, for those of you concerned with a cop "sticking a mirror under your car", how difficult would it be to fabricate some "faux cats" and weld them on there?

 

Fake cats would be fine for the "visual" portion of the inspection, however when the dynamic or OBD II tests are performed, the vehicle PCM will most likely tell on you. It will see poor cat efficiency and show up in the "cat. efficiency monitor" as a failure, and will eventually turn on the "ck engine" light.

 

That's why you turn off the rear O2 sensors. [img]style_emoticons/<#EMO_DIR#>/04.gif[/img]

 

Unfortunatly, the PCM knows youve tuned them off, and so will the program thats used during emissions test. Its getting tougher & tougher to get around these inspections.
The people who set up these programs aren't just suits,
they're gearheads too, and they just as many tricks as we do.

 

<div class='quotetop'>QUOTE(lci2 @ March 1, 2006, 5:15 PM) Quoted post</div><div class='quotemain'>
Unfortunatly, the PCM knows youve tuned them off, and so will the program thats used during emissions test. Its getting tougher & tougher to get around these inspections.
The people who set up these programs aren't just suits,
they're gearheads too, and they just as many tricks as we do.
[/b][/quote]
Well then, I'm glad I don't need an inspection for 6 years! [img]style_emoticons/<#EMO_DIR#>/thumb.gif[/img]

 

Agreed!

 

The actual difference in sound from no cats to the high-flow variety is very minimal. I had the Bassani off-road x-pipe first and then added the cats. Very hard to tell. BUT... there is almost no drone now with the high-flow cats on and that resonance sound under hard acceleration is gone. I think you would be ok having an off-road h-pipe, but I really think that the x-pipe needs the high-flow cats. An x-pipe is just inherently louder because it flows better than an h-pipe.

 

X pipes are louder but H pipes are deeper [img]style_emoticons/<#EMO_DIR#>/04.gif[/img] ... and I'm scheduled for an echeck in 09, I think. [05 MY+4yrs]

 

Come inspection time, I'll just throw the stock pipe back in. Throwing in the H-pipe was cake..

 

<div class='quotetop'>QUOTE(lci2 @ March 1, 2006, 7:15 PM) Quoted post</div><div class='quotemain'>
Unfortunatly, the PCM knows youve tuned them off, and so will the program thats used during emissions test. Its getting tougher & tougher to get around these inspections.
The people who set up these programs aren't just suits,
they're gearheads too, and they just as many tricks as we do.
[/b][/quote]

I've always been told that the emissions facility just uses a OBD scanner that checks for emission codes. As long as you aren't throwing a CEL, you will be fine.

 

hey, you guys with the H-pipe, do you all get that "tinny" sound? It seems most noticeable when the car is first fired up, then subsides somewhat as the car warms up.

 

I live in Texas... I've had cars without cats..... to be honest I tookt he risk and just told myself not to worry about it... Here in Dallas I've never seen or heard of any cop looking under your car with mirrors for no cats....

 

Any California guys ever have cops do the mirror thing?

 

not yet, haven't been stopped for being loud...and I am goin on a year with running no mufflers. about 6 months of no mufflers, no cats, headers, and xpipe.

 

I've never even considered looking under a car on a stop. I'm not the EPA police. I'm considering going catless as well...now that my area in Ohio has stopped emissions testing I think it won't be a problem.

I'm a little concerned about how loud it will be with the magnapacks (which I have now)...catless and the long tubes I plan on installing at the same time.

 

<div class='quotetop'>QUOTE(4511.21 @ March 2, 2006, 10:55 PM) Quoted post</div><div class='quotemain'>
I've never even considered looking under a car on a stop. I'm not the EPA police. [/b][/quote]
I'm assuming you are a LEO?

 

<div class='quotetop'>QUOTE(Rebel73 @ March 3, 2006, 11:44 AM) Quoted post</div><div class='quotemain'>
I'm assuming you are a LEO?
[/b][/quote]

Yes...suburban LEO. Come to think of it...only problem may be with the state troopers in my state but even that would probably be rare.

 

<div class='quotetop'>QUOTE(4511.21 @ March 3, 2006, 12:55 AM) Quoted post</div><div class='quotemain'>
I'm a little concerned about how loud it will be with the magnapacks (which I have now)...catless and the long tubes I plan on installing at the same time.
[/b][/quote]

Trust me... that will be VERY loud. I had no cats at one point with the Magnaflows (not the Magnapacks) and had the stock headers and it was almost too loud. Adding LT's and having the packs will make it much louder for sure.