oops... double post/editing mistake

 

Right, I like straight pipes too when they're set up right. Sounds good and you don't have to spend a few hundred on fancy mufflers. Another favorite is glasspacks, they can be had for less than thirty bucks apiece and sound good when mounted a few feet away from the engine. Mine are under the back half of the cab and the pipe coming off them only runs to the front edge of the bed. Now without that pipe behind them, they would burble when cruising and RAP when I got on it, but it also had a drone in the cab so I compromised and ran the pipes back to where they are now to kill the drone, losing my wide-open rap in the process.

Screw backpressure... what you want is FLOW

The reason engines lose torque when putting bigger pipes in is because with a larger pipe, the exhaust can take it's time leaving and you lose the scavenging effect at the engine.

Put in some narrower pipes, and you still have the same amount of exhaust trying to leave the engine, but now it moves faster since the smaller pipe forces the exhaust to travel at a higher flow rate, which helps get the exhaust out quickly.

 

I ran a stock cat with no muffler and it was still pretty quiet. Then I ran stock cat to a flowmaster 10 series 3in in dual 2.5in out and it almost seemed louder and sounded much better. Even if youre on a budget spend the extra 60 bucks and buy some kind of a muffler because straight pipes with a cat doesnt sound very good (although it is louder and cheap). Ive never heard straight pipes with no cats so I dont know how that sounds. Now I have a ten series with a Y pipe and no cat and ya as Diesel Brad said, its obnoxiously loud, but I like it. So YES a Y pipe will be able to replace the cat. I second buying a magna flow Y pipe.

 

I'm sure you have seen this before in the other post, but here it is again anyway.

 

earkermeld, do you have a pic of the front of the exhaust from the manifolds does yours go into a y-pipe, or is your true duals?

 

Here is where they go together.

 

Straight pipe it if you want to be like the high school kids that think noise = power. Catted y-pipe, a muffler of your choice, and a tailpipe configuration of your choice and you'll be set for many years. You get what you pay for, exhaust shops use thicker walled pipe than the little sections you can buy at the auto parts stores. Make sure it's welded and you won't have to worry about it for a long time.

 

Why won't the back-pressure myth just die off already. You DO NOT want back-pressure in a 4 stroke engine at all. You want it to flow and to scavenge the exhaust. As to the original poster I don't know if you could clamp it all together. If you want things to be easy but expensive go with shortys and one of the magniflow Y pipes. Some of the Y's have cats and some don't but they are really really expensive regardless. Another way to do it if you wanna spend money on headers is long tubes and a custom made single exhaust either done up yourself or by a shop.

 

This explanation comes from F100beatertruck and is the best I have ever heard.
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Grrr... It's NOT back pressure you need...

Why, why won't this myth just die already!

Exhaust is a series of pressure waves with high and low pressures - peaks and valleys. There is also a mass that goes with it to create momentum. When all those pulses exit the exhaust system there is a reverberation or a back pulse that goes back to the engine. There's a lot more to exhaust systems then just dumping toxic fumes out the back. You need to manage the velocity and also the thermal energy.

So... When someone chops out a muffler and the car runs like crap because they've upset that careful balance, they assume it just needs a cork in the system to run better... Big, open pipes can kill the velocity and allow the exhaust to cool down and become more dense. So it piles up in the end of the pipe.

Longer pipes in general are a good idea because with velocity you can increase scavenging due to the mass of the exhaust stream. Any large change in the cross section of the exhaust looks, to the engine, like the end of the line. Mufflers also build heat and help thermal management. It also helps smooth the pulses out. This is where crossovers, x-pipes, etc all come into play and it's also the theory of the Tri-Y headers. Get all the pulses to nicely line up and smooth out. However, this is always changing because of the changing in RPM. Larger engines and higher RPM engines need larger pipes to manage all the air and keep the velocities in the sweet spot. X-Pipes, crossovers, etc can be placed in different locations to favor a specific RPM. IIRC the further back they are the more it favors the low end.

There is a ton of science to this and it has nothing to due with corking up the pipes - aka back pressure. Sorry for the rant but it's one of my pet peeves. It's right up there with people who bash brands without any specific first hand reason. My father refused to even consider a Ford, saying there were junk because he learned to drive in his father's poorly maintained 1949 Ford around 1960 and it kept breaking down. I finally got him into an Explorer and he loved it.

 

lol so from my understanding then back pressure is bad, so straight pipes would give you the most power? also would i be able to just clamp my exhaust?

 

Strait pipes may not scavenge properly. Remember, pressure waves-ebbs and flows-peaks and valleys. The absence of any mufflers will not give you that.

 

And yes, you can clamp but you probably won't be pleased with the durability.

 

how did you get the two pipes to lay beside each other?, the stock exhaust is on a vertical into the cat.

 

I don't quite understand the question. The cat and everything forward is bone stock. I simply cut the single outlet off the end of the cat and welded a plate with 2 pipes to the end of it. 2 1/2" dual pipes and 18" glass packs for the rest.

 

Oh, I understand. 302's and 460's have different set-ups for that.