Need knowledgable opinion

[firengnred]

So here's the deal..... I ordered the Magnaflow Comp. Series Axle Back exhaust and perforated X-Pipe to replace stock L-99 system. After receiving and installing, sound was awesome and torque was definitely increased. I was loving it. Then I found out I had been sent a dual straight through muffler instead of the perforated X-Pipe. Contacted retailer and they sent me the correct muffler and paid for the shop to swap out the wrong muffler. What a disappointing difference. Now the car sounds barely better than stock and has lost the torque it had with the other muffler.

Now someone correct me if I'm wrong. I understand back pressure helps with torque and I believe that is why I could feel more torque with the straight through muffler. No crossover meant more back pressure and more torque. But now that I have the X-Pipe crossover, less back pressure so less torque. The only mods are the exhaust and Super chips tune. I intend to put on a CAI Inc intake which should be arriving this week and eventually a maggie. Undecided about LTH as I live in Ca.

So my question is, can I expect the torque to return with the intake swap, as this will allow more air in to build more back pressure? Is there a real advantage to the X-Pipe vs the straight through? I know the maggie will give me LOADS of torque but could it be more with the straight through? I guess what I'm getting at is, should I keep the X-Pipe or the straight through?

[2ndgenz28]

I prefer straight, years of self experimenting with every different car I ever owned and many different engines has that kind of set up installed on everything I own.

[SGOS252382]

I think your car just seemed faster because it was louder. I dought you would gain or lose any HP on a dyno. And I'm sure your car would run the same times at the track with each setup.

[firengnred]

You are correct about it being louder but it definitely had more torque. launches were much more forceful. You could certainly feel the difference.

[Johnwayne]

i concur

[axis]

Backpressure making torque is a myth. In reality, the Xpipe should have been the part that made more HP since it aids in scavenging exhaust. The more air you run through the motor, the more HP you'll make. I concur with SGO in that noise will definitely heighten your butt-o-meter.

If you don't believe, look at Jannety's LT thread. He tested 1 3/4, 1 7/8, and 2in headers, all the same manufacturer. The 2in headers made the most HP AND Tq.

[toehead93]

if you really were making more torque it probably had more to do with air temp than the muffler. If the the intake air temp increases then the ECM pulls timing. Even if the outside air temp is the same you can see higher IATs just from idling.

[4xchamp]

I don't believe a stock LS3 would see any significant gain from changing the exhaust . In my experience changes of this sort help modified high reving motors . The stock pipes are ok .
My LS3 is presently bone stock . One of my friends bought an L99 , he tells me his $1200 exhaust added 35 hp , his $ 400 cai added 30 hp , $200 pulleys 10 hp and finally the $400 tuner for 25 hp . He says thats 100 hp for $2200 bucks . Can it really be that easy I ask ?
We finally played a little and I edged him every time .
I'd love to see unbiased dyno tests on various modifications and I bet most aren't worth chit .
To see real gains you need cam , blower and cubic inches .

[wbt]

Originally Posted by axis

Backpressure making torque is a myth. In reality, the Xpipe should have been the part that made more HP since it aids in scavenging exhaust. The more air you run through the motor, the more HP you'll make. I concur with SGO in that noise will definitely heighten your butt-o-meter.

If you don't believe, look at Jannety's LT thread. He tested 1 3/4, 1 7/8, and 2in headers, all the same manufacturer. The 2in headers made the most HP AND Tq.

^^^Man knows what he is talking about^^^

[firengnred]

bump

[Roger Ramjet]

I believe the straight through muffler made more torque during launch. And, I believe the X muffler would make more high RPM horsepower. All this has to do with organ pipe theory and the reflected pressure waves in the exhaust system. The straight muffler creates long wave lower frequency pulses which will boost cylinder pressure below the camshaft dictated peak torque airflow. I would expect this to be most noticeable 1000 RPM below peak torque. Max torque for a L99 is 4300 RPM. So, the straight exhaust should be most effective below 3300 RPM. With the factory tune Torque Management active below 3000 RPM the torque improvement would be undetectable. But this car has been tuned (Torque Management reduced) so the low RPM improvement should be noticeable.

[flyby]

Many people have changed types of axle backs from the stock which includes the mufflers. On the dyno no difference. The engine is a glorified air pump. The more air you flow through the more hp it is just that simple.

[The_Blur]

Originally Posted by flyby

Many people have changed types of axle backs from the stock which includes the mufflers. On the dyno no difference. The engine is a glorified air pump. The more air you flow through the more hp it is just that simple.