jicl55

As far as not the same as straight pipes, I don't think it would be the same, but you might decrease your back pressure somewhat by gutting them, I'm not exactly sure. And the muffler guy told me about 1.5 lb per cat, so that is probably only an estimate or an average, but secondary cats or any other cats are a restriction point somewhat. You remove them, more free flowing, less back pressure.

jicl55

....and I would go with this setup if it weren't for California emissions..... another reason the rear cats went back in.

chawkins2001

new system is on and it is SUPER aggressive. I will get a clip up in this thread tonight if my camera does not take a dump on me.

chawkins2001

Well, guys I ended up gettting Kleeman headers, leaving the stock secondaries in place, 3" straight pipes that replaced the resonator, and magnaflow magnapacks with new tips outback. Magnaflow Magnapacks are basically straight pipes with some slight fiber glass packing but over time that wears down and becomes straight pipes. They car has zero rasp at all which I am very surprised but has a ton of bass. The drone inside the car is substantial which I like but if you carry passengers alot, I would not recommend this setup.

I went into a undercover garage last night as I had to get groceries from the store and set off several alarms starting the car up and cruising out the parking lot

Like I said, not many members will like this setup as it is very much in your face, loud and obnoxious, but I love it, and have had alot of smiles and frowns with it so far. If I decide to gut the secondaries, under WOT it will be as loud as open headers but cruising will just have a low rumble... I will get a clip up very soon as I want to do drive by's, reving, idle etc so you can get the full picture. Right now I am very satisfied with the setup and will let it wear itself in before I change anything else. I am sure the 180mm pulley and tune will add even more rumble.

Hazim

I replaced my exhaust pipe with a 3" pipe all the way from the headers to the stock AMg muf. no cats no res. just 3" strieght pipes, but I lost the low end torq,



What should I add an H or X to get some back pressure, for the low end torq?
Thanks

chiromikey

a set of cats. a set of good 200cell count high flow buggers should do the trick.

chawkins2001

if you get a tune, you will pick up your lost tq plus some. cars without cats once tuned generally make more power.

BlownV8

"Back pressure" is bad in an exhaust system. That means that there is too much restriction in the flow. What is happening when you go to an exhaust that is too large is that the exhaust velocity is slowed down thus reducing your hp. Too big is not good! It's all about exhaust velocity and exhaust flow. You want the greatest flow and the greatest velocity.

When the exhaust slows down due to an over-large exhaust, the air cools and does not move as fast as it should. A hot air mass will move much more quickly than a cold/cooling air mass. Remember, a larger exhaust is not always a good thing but one that is too small is bad too!

http://www.veryuseful.com/mustang/te...Scavenging.pdf
http://www.miata.net/garage/KnowYourCar/S4_Back.html
http://www.popularhotrodding.com/eng...exh/index.html

Hazim

I have noticed the temp of the engine droped by about 3 to 5 digrees with the 3".

Some guys are telling me to get and H pipe for the lowend tq.

So you guys think i should get it tuned? Do I have to send my ecu or i can get a good pulg and play chip?

I only have K&N filters, 3" strieght pipes with stock AMG muff.

sorry for going of the topic.

chawkins2001

No problem, it is my thread and want to help. A tune will help as it will get the most out of your combo as possible. I pulley will greatly increase your lost low end torque. I would do that before you do the 200cel cats as it should be cheaper and yield a ton of power and torque.

MRAMG1

Good information my friend
Espically the first link, but keep in mind that we are talking about FI motors here so there is a positive pressure present any time the intake valve comes off its seat. Hence NO vacume ie ever present during the overlap face.

See yeah

Hazim

Thanks guys for your help.

BlownV8

Not the case, the engine is actually only under boost for, most owners, less than 1% of the engines life. The other 99% of the time the engine acts as a normally aspirated powerplant. I know what you are trying to say but exhaust basics of flow and velocity are still valid....even in a forced induction engine.

chawkins2001

This have been proven to many times over in the mustang world, no cats equals better power once tuned. After all the is a 5.4 V8 with a blower, very similar setup to the GT500 except it is SOHC.

GRAFH

I'm installing dual 3" ss from after market header back. All v-band, no crappy welds or compression fittings. This will make for easy removal when I sell the car. I have not decided on which cats yet. I was thinking of something from http://www.randomtechnology.com/ Mufflers are still up in the air.

BlownV8

If you fit an exhaust that is too large, you will lose velocity and lose power. If you fit one that is too small, you will lose flow and lose power. You want the highest flow with the highest velocity. If that equation works for removing the cats, so be it. Obviously the exhaust on the Mustang has a restriction, catalytic converters, that can be removed and thus increases flow while not hurting velocity.