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straight piping

3K views 26 replies 14 participants last post by  FunktasticLucky 
#1 ·
i read the charts posted and everything, but is open straight piped? i want to straight pipe my car as i just got it smogged so i can get away with it for a year. would this hurt or improve performance by removing the 3 cats and doing true dual exhaust with either 2 or 2.25 inch pipping.i have 4.6 97 sport.
 
#3 ·
2" dual is fine for stock.. keep the first two cats at least.. no sense killin ozone while we still have it.. and no, i'm not a tree hugging hippy... just no point screwing sh!t up more if we don't have to.. not like it will help you anyway. no front cats will throw a code w/o a tune

get an H or X pipe to reduce some of the noise and help balance it on the way out. H can be done at a shop, X may need to be purchased unless you get a mid mount muffler w/ tru x (magnaflow) or the shop fabs one up
 
#4 ·
well what i was thinking was have it true duals and then come out the side infront of the rear tire and the ends cut like this / towards the tires. the ends of course would be chromed. what i might do is use my glass packs i bought to slip past smog. and but them in the center area but staggered so they'll fit
 
#8 ·
why not put a muffler on there to make it sound good and legal at the same time?
 
#9 · (Edited)
As a smog tech in vegas, I'll tell you right now I'd report it to dmv or fail it upon inspection or both.

Just do a decent set up like many others before you, x pipes are your friend whether they are built into a muffler like the dynomax and magnaflow units or alone.

Keep your factory primary cats if they aren't clogged or at least put some aftermarket high flows on there.

If you don't want to be hastled by the cops and instantly pulled over by the bike cop or cruiser next to you at a stop light I'd think twice about side exit and no mufflers. Due to the california law that states that the exhaust must exit behind the rear wheels.

But regardless its your car, do what you want but be prepared to pay the price when you need your next emissions test or need to pay a ticket for "Vehicle modified for noise" or some such garbage.

Many people squeek by the california visual because they keep cats and exit their exhaust out the back or pay off the smog inspector.

If you choose not to listen to the advice given to you by myself and many other on this forum than learn to enjoy your drone and any legal inconveniences.

Also it is illegal to remove or tamper with any emissions related devices (cats, egr, pcv, evap,etc...) and is illegal to resell a tampered vehicle without replacing any and all tampered devices with new OEM pieces. It is the sellers responsibility to make sure all items are intact and appear to be functioning not the buyers. So if you hack up your exhaust and sell the car 5 years from now even as is, the buyer can turn around and sue you for any and all necessary emissions related repairs due to you removing them.
 
#10 ·
You don't want to go catless. Sounds like complete poo. Here's proof:

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If you just want louder, you're better off just cutting off the mufflers (but this too sounds like poo, just not as much poo-sounding as no cats). Example:

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You're better off just getting a legit exhaust.
 
#12 · (Edited)
You don't want to go catless. Sounds like complete poo.
after watching that vid i thinkin i'm not going to like the "tinyness" of it. thanks for the vid. i want something louder but sounds decent im pretty much running with no mufflers i put 22" glass packs that are straight through i may just figure out what my buddies have done and copy them as they don't sounds half bad. i like the sound to be honest of the muffler cut off as i drove around 2 days with out them on and other then the popping it wasn't to bad sounding.

EDIT: what high flow cats would you guys suggest? i've taken your guy's advice not because of legality but because of assssy sound. basically i want my car to roar like the mustangs do
 
#13 ·
You won't be able to get the "mustang sound" with the single exhaust.

I rather like the mellow sound that comes through my Dynomax catback setup, it also sounds rather agressive under throttle, but not too loud to disrupt conversation, and zero drone on the highway. Considering that the rear muffs are fiberglass filled, I'm sure that the sound will get louder over time too.

Though I do have a much louder setup on my P71 Vic. I replaced the cats with straight pipe, and installed long glasspacks in place of the muffs. This setup definitely improved the top end, but with the 2in full tail pipes, there was a resonance that killed my bottom end. I then cut off my tailpipes and installed turndowns right in front of the rear axle. This helped out tremendously. It gave me back my bottom end and more, and killed off that "blatty" resonance. There are times when it gets so loud that all conversation must stop, but that depends on my right foot. Also, it drones pretty loudly on the highway, but I don't mind because I just turn up the radio.

I would say that high flow cats, 2 inch pipes, glass packs, and turn downs behind the rear axle would make for a good sound with less noise in the cabin and less drone on the highway (as long as there are no tight bends, that might give you the "blattyness" that I experienced). It still won't sound quite like the new mustangs, but they have a much different and probably more costly setup.
 
#14 · (Edited)
here is my staight 2" Dual setup with Custom H-Pipe, Flowmaster and Stock Engine.
Best played over Home or PA system. lol
Hope that help's some.
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#17 ·
here is my staight 2" Dual setup with Custom H-Pipe, Flowmaster and Stock Engine.
Best played over Home or PA system. lol
Hope that help's some.
that sounds meeeeaaaaannnnn. what flowmasters? 40 delta series?
 
#15 ·
Hey MAIC, paint looks great and your exhaust sounds really good. Anyway, I have to disagree a little about no cats sounding like junk. My car doesn't have them nor does it sound like mikemelancholic's clip. Maybe it's because of differences in setups (mine is in my sig). Obviously on some arrangements no cats sound like junk, but mine is surprisingly mellow until i punch it then it screams. It doesn't crackle one bit especially after a few miles were put on my muffler. I will admit that it is a little loud for my tastes, but I got used to it. I should also note that my gf doesn't really like riding in my car because of it. I would love to post a clip, but the car is currently somewhat apart and hibernating.
 
#16 ·
:bawling:
In the beginning they just cut my cats open and cleaned them out. After a few weeks i went with a different exhaust shop and had them removed completely. this made a noticeable noise reduction on the inside. This may be something to think about while on it.
 
#21 ·
you suck i hate you and am extremely jealous. i hate californian politics there's no common sense involved at all anymore.

maic: did you loose any torque on the bottom end taking off all the cats?
 
#23 ·
Well for me, my car is stock. all i did was cut from behind cats and install two pipes with flowmasters at the end. I love the sound dident loose any power no check eninge lights and not two much money. all I need now are headers
 
#27 ·
Here is when we finally got it started. This is braincoated ported manifolds with 2.25" Mandrel bent downtubes and dumped right after the high flow cats.

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Here are some Dyno Pulls with the exhaust on it. It's expanded to 2.5 inch with H Pipe to 2 Borla pro XS mufflers.

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