How much hp could I loose w/ cats?

forrealb50 · Jan 6, 2004

I need to quite my exhaust and I'm going to start with cats because I need them. Right now I got FMS short headers, off road h-pipe, and flowmaster 2 chamber cat-back. If I added a h-pipe that is 2 1/4 w/ high flow cats instead of 2 1/2 off road h-pipe how much hp could I loose? My exhaust almost blows my brains out

TK_05 · Jan 6, 2004

i would think hardly any.. deffinately not enuff that you would feel a difference... but it will be alot quieter..

5.0 Nostalgia · Jan 6, 2004

None. My car posted better times with the factory pipe. They don't make a difference unless you have serious mods.

charlesw6954 · Jan 6, 2004

2 1/4?? get 2 1/2 high flow converters. i had shorty headers, catted h-pipe, and magno mufflers on my old stang and when i changed to o/r h-pipe all that o/r hpipe did is just loose lower end torque and make my car really loud.

forrealb50 · Jan 7, 2004

Do you think putting the stock 2 1/4 h-pipe w/ cats on will make me loose power? Because it is free and just sitting in my garage...

sleeper89 · Jan 7, 2004

...you could always cut two cats from the stock h-pipe!! i know it won't help you to pass emmissions or anything but it should make you quieter.

-steve

charlesw6954 · Jan 7, 2004

oh i thought you were going to buy one. my catalytic h-pipe cost me $350 thats before i knew there wasnt emissons.

5spd GT · Jan 7, 2004

How bout get a quieter muffler...

but if you have the stock hpipe and its for free I would just go for that...

David

90mustangGT · Jan 7, 2004

5spd GT said:
How bout get a quieter muffler...

but if you have the stock hpipe and its for free I would just go for that...

David

That is what I am saying. There are alot of different mufflers out there that arn't stock. Since your in the car, it's probally drone which is bothering you. Shortie headers, O/R H pipe, and flows is the perfect combo if you want drone. I've heard the dynomax's are good for the price and magnaflow's are nice and quiet at idle, until you open ut the throttle. A catted H pipe will hurt sound quality more than quiet it.

DirtyD916 · Jan 7, 2004

bassani's catted x-pipe actually made my friends ride sound louder and better. so its all opinion then

siege · Jan 7, 2004

I think its more the mufflers than the lack of cats. I had 3ch flows with o/r h-pipe and mac shorty headers and it wasn't loud. switched to Borla Pro XS mufflers and its still not very loud, but sounds better and more power. you'll still have a stupid drone with the stock h. I vote for new mufflers

87TTopGT · Jan 7, 2004

I just put the 40 series Delta Flows in mine today and it sounds AWESOME!
Of course my engine is still stock, and so is the H-pipe- I had them put six-inch turndowns on it, and there is NO DRONE. The only thing is just a hint of resonance around 900-1000 RPM, but who drives in that range? I was worried that it would be louder than I wanted, I was looking for something like the 50-series sound like, but got these on Ebay brand new for $57/ea plus $17 shipping and couldn't pass it up! GREAT muffler, love it!

YardSpecial · Jan 7, 2004

I would say put cats back on.

03 Cobra makes 400 @ the crank with cats.

For me getting a ticket for no cats is not worth maybe the 10 HP I get with offroad pipes !!

Your car being louder is the clue to the man to LOOK !! (told to me by the SMOG Nazi's)

I run Bassani 2 cat X.

charlesw6954 · Jan 7, 2004

hey 87topgt you got the 40 series? if so man with a stock engine and only the mufflers and rest of your exhaust is stock. well well well its gonna get really loud when you put o/r h pipe, and headers cause damn my girlfriend can hear me like a half mile away from her house. thats funny

CobraGT87 · Jan 8, 2004

90mustangGT said:
I've heard the dynomax's are good for the price and magnaflow's are nice and quiet at idle, until you open ut the throttle. A catted H pipe will hurt sound quality more than quiet it.

I run dynomax ST's with magnaflow high flow cats with angled turn downs on the muffler ends. it's is FAR from quiet at an idle, plus I get no drone at 2k and no gas fumes. Magnaflow makes the best high flow cats IMO, (pricey but IMO well worth it). I had my back pressure tested with this setup and it was only 1.3 which is pretty darn free flowing, and it was cleaner out the pipe than the stock cat setup on the smog machine with the only thing changed being the cats.

CobraGT87 · Jan 8, 2004

Cavallo said:
I would say put cats back on.

03 Cobra makes 400 @ the crank with cats

If i'm not mistaken, the 03 Cobra makes 370 at the wheels stock, and a few simple mods puts em at 400 to the wheels.

Scott

JadeFalcon · Jan 8, 2004

However you miss the point that a full exhaust adds like 30rwhp on the 03's. Alot of restriction there, ever heard one stock? quieter than a GT.

I would say that cats do restrict you somewhat, you are pushing exhaust threw a honeycomb catalyst, there is restriction, but not a lot, however, if your using clogged cats, or old ones, there might be huge losses of power.

You have to be moving A LOT of air to have big benefits from no cats, forced induction normally sees the biggest differences, I know I did.

CobraGT87 · Jan 8, 2004

JadeFalcon said:
However you miss the point that a full exhaust adds like 30rwhp on the 03's. Alot of restriction there, ever heard one stock? quieter than a GT..

Not flamin at all.

What point did I miss? I said they make 370 STOCK and with a FEW mods they make 400 wheel. Yes I have heard one. My brother owns a red 03 Cobra vert.

I would say that cats do restrict you somewhat, you are pushing exhaust threw a honeycomb catalyst, there is restriction, but not a lot, however, if your using clogged cats, or old ones, there might be huge losses of power..

How well they flow depends on who makes the HF Cats, but with only 1.3 back pressure, it sure isn't much in my case as thats very close to what a race car with no cats and race mufflers make
according to Ed Curtis, He was even surprised how low it was for my setup.

You have to be moving A LOT of air to have big benefits from no cats, forced induction normally sees the biggest differences, I know I did.

I fully agree

Take Care,
Scott

87TTopGT · Jan 9, 2004

charlesw6954 said:
hey 87topgt you got the 40 series? if so man with a stock engine and only the mufflers and rest of your exhaust is stock. well well well its gonna get really loud when you put o/r h pipe, and headers cause damn my girlfriend can hear me like a half mile away from her house. thats funny

I have the Delta Flow 40s. Do you have the original 40 or the delta flows? Original have one baffle like this < in the chamber, where the delta has three like this <<<. Flowmaster says the deltas are not as loud and the baffles cancel out the drone- I've heard 40s before and these are not as loud, but still have a powerful rumble at idle and roar when you push the loud pedal!

YardSpecial · Jan 9, 2004

My point was the Cobra has the same exhaust and put down 400 HP at the crank.

Cobra's lose torque and boost when the bigger exhaust is installed.

Doubt there is any NA cars droping 350 HP to the wheels that need a offroad pipe.

ALL Cats are High flow, aftermarket use 2, 2 1/2" Cats with 2 1/2" pipes the only differance.

U open one end up, U need to open the other end to gain what U lost.

How much hp could I loose w/ cats?

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