[larry davis]

What's everyone's experience w/ this muffler?
Did it make decent power?

I've got the entire 2.5" Flowmaster system to put on my 78 T/A w/ 428 @ 500HP.

Thinking about ditching the pieces from the collectors back to before the over the axle pipes in favor of the 3" DR. GAS crossover. [img]/infopop/emoticons/icon_biggrin.gif[/img]

[larry davis]

What's everyone's experience w/ this muffler?
Did it make decent power?

I've got the entire 2.5" Flowmaster system to put on my 78 T/A w/ 428 @ 500HP.

Thinking about ditching the pieces from the collectors back to before the over the axle pipes in favor of the 3" DR. GAS crossover. [img]/infopop/emoticons/icon_biggrin.gif[/img]

[sherm455]

I can't speak from experience since I haven't istalled this system yet, but I called the flowmaster rep and he said the sound is in between the 40 and 50 series mufflers. The flow through the transverse muffler is almost equal to the true dual 40 series system. He said about 90% of the flow rating of the 17149 system. I was impressed with the quality of the bends going into and out of the transverse muffler. Not sure if this helps or not. [img]/infopop/emoticons/icon_smile.gif[/img]

[larry davis]

It looks like a quality system. The radia of the bends are smooth & correct. I blasted & stainless coated my entire system (exterior).
I'm really impressed w/ the Dr. Gas crossover, it should be a lot better than the standard H type.

[sherm455]

I am debating weather to put in a X pipe. I see they supply the H-pipe ready to go. I am using HO round port manifolds with approx. 500HP. I hope I am not losing too much power with is setup. I just need to find a set of 2.5 downpipes to finish it.

[Rocky Rotella]

You guys sound like you need to see and hear this! You may need to cut/paste to get them to work.
http://www.geocities.com/rotella31/x1.jpg
http://www.geocities.com/rotella31/x2.jpg
http://www.geocities.com/rotella32/2041.wav
http://www.geocities.com/rotella32/2043.wav
http://www.geocities.com/rotella32/accel.wav

My dad's 72 T/A uses the 42582 side inlet/outlet muffler with custom bent piping(it's the short clip). My 76 T/A uses the 17104 kit with the 42585 muffler. I'm very pleased with the sound and performance. Tom Hand's CD has an excellent track of the 42582 muffler. That muffler, which was ours and loaned for the testing, sounds identical as when it was on the car.

Hope this helps. Let me know if I can help you with anything at all.

[sherm455]

Rocky-
Thanks for the sound clips. It sounds a little quieter than the 17149 dual kit. How is the interior noise? Do the tailpipes help dampen the sound somewhat? If you look in the past posts, there seems to be some contoversy with if the X-pipe really works or not.

[455Dave]

sherm455:

I ran the Flowmaster transverse setup for almost three years. During that time, the 455 got various improvements including headers. The headers didn't seem to make much difference so I was thinking that the exhaust system could be restrictive.

I installed the Dr Gas system and I noticed idle vacuum dropped a lot till I richened the carb up. I swapped out the secondary rods Friday and the car pulls in 2nd gear like never before, the car had always seemed weak after first gear. I previously tuned the carb on a dyno with an A/F sensor to get the mixture right on the old exhuast but it seems to flow a lot better now.

I had a bit of fun with the car since it was running so well. It won't hook up at all with 255s even without hitting the secondaries. I was loving the car till the heater core blew out so the T/A is sidelined till I can fix that.

I'm not saying that an X pipe will help every car, but it seems to be helping mine. I don't know if it was the transverse muffler or the the H pipe, but something is working better now.

The Dr Gas and the Walker mufflers gave the car a much deeper tone at idle than the flowmaster and its a LOT quieter at cruise now.

Just my two cents.

Dave

[ January 27, 2002: Message edited by: 455Dave ]</p>

[SLOW 77]

I had the Flowmaster exhaust sytem but I even added 3" headpipes all the way to the rear seat. I switched to a Dr.Gas 3" X Pipe and 3" Torque Technologies tailpipes, and picked up 2mph and .1-.2 in the eighth mile, all this and it is a lot quieter. I would go for this mod, this helped drop my E/T, and noise, good bang for the buck. Cut your old exhaust of carefully and you can sell it easy, as it fits a variety of cars.

[larry davis]

Dudes, I'm planning on using the 3" DR. Gas X pipe from my 1 3/4" Jethot Headman collectors, into the 2.5" pipes that go over the axle & into the transverse muffler.

455dave, so your performance picked up switching from the Flowmaster transverse muf? [img]/infopop/emoticons/icon_smile.gif[/img]

[455Dave]

I can't really say it was only the muffler since I swapped complete systems. It sounds like the Dr Gas and the tranverse muffler is a good combo though.

What I like about my setup:

Deeper sound and much quieter.
Room for wider back tires.
Exhaust pipes now angle down near the back of the quarter panel so I can run factory style splitters.
I can get to my axle cover.
I can drop my whole exhaust with 12 bolts.
Easier to install an electric fuel pump near the tank.

What I liked about the transverse muffler:

Very clean look, no ground clearance issues.
No visible mufflers.
Had a good sounding idle with the cam I'm using
Easy installation with headers.

Be careful when you install the muffler so it clears the axle. I had a few contacts before I got it right. Also, the passenger side tailpipe seemed to be an inch or so short when it went into the muffler. It will all fit, but I wish it had more pipe in the muffler.

Larry, the big reason I swapped it out is I got tired of the wife and kids complaining the car was too loud. I liked it. [img]/infopop/emoticons/icon_biggrin.gif[/img]

Now it's quiet but it runs a lot better.

Dave

[larry davis]

Dave, you mean there's a back seat in these T/As?

No sh!t? People actually ride back there (sober)?

[img]/infopop/emoticons/icon_wink.gif[/img] [img]/infopop/emoticons/icon_biggrin.gif[/img]

[Jim Hand]

Sherm455,
On the contrary about the effects of the X Crossover, there is no controversy about the track tests we conducted with the Dr. Gas X Crossover. We made three runs on a rented track with a good H Crossover in place. We replaced the H with the X and used the same mufflers and tailpipes - the weight was identical to within 5#.

We again ran three runs with the X - the car ran so much quicker and faster, we thought something was wrong. So we replaced the H for the seventh run and found the same result as the first three runs!

As has been said the results can vary but every car we have seen change to the Dr. Gas X crossover, has run quicker!

For a complete report on these tests, and other muffler and tailpipes tests, check out the address below.

In our opinion, the single transverse muffler will cost some amount of performance as compared to true dual mufflers. It may be only hundreths of a second, but if you are after maximum performance, good dual mufflers will be best.
Our recent flow tests on mufflers showed a significantly higher back pressure for the transverse muffler as compared to one regular higher flowing muffler. And considering that dual mufflers are available, that could make a difference in performance.
Jim Hand


X Crossover Tests

[ January 28, 2002: Message edited by: Jim Hand ]</p>

[455Dave]

Larry,

Nothing like picking up the youngest from high school in the T/A. I make sure to get the car in second at least a block away so they can hear the 455 run up and then coast down for the turn in. In a sea of SUVs, minivans, Mercedes and BMWs, the primered pig rolls up with the throbbing exhaust. All the kids stare, but never say a word. My youngest girl is almost in tears from the embarrasment of packing her friends into the back seat where the Flowmaster resonance does (used to) it's worst. A couple of blips on the throttle (you don't screw around with kids in the car) demonstrate the poncho power under the hood without ever exceeding the speed limit.

Dropping kids off in gated communites with guards, seeing parents peek out between the curtains; yes I put passengers in the back seat, teenagers only, but it doesn't happen often. They must have bad memories or really need the ride home. [img]/infopop/emoticons/icon_biggrin.gif[/img]

Dave(I love being a Dad)

PS: There is no back seat in the car right now. [img]tongue.gif[/img]

[sherm455]

Jim- Thanks for the link to the crossover comparision. It looks like you have to run a crossover of some type, be it a H or X pipe. The controversy I read about, was in the archives under X pipe. A member named Gach said it doesn't work and others had some varying results. I must say your test were at least conducted under a controlled environment, as best as you can probably get at a dragstrip. Was wondering if you have to rejet carb after each muffler test series? [img]/infopop/emoticons/icon_smile.gif[/img]

[larry davis]

sherm, as you are fairly new to the BB; there is an accepted concensus within' our ranks that Mr. Gach is full of it.
Personally I can niether confirm or deny this, as I don't know him. But many credible members don't have much good to say about him.

IE: consider the source. [img]/infopop/emoticons/icon_smile.gif[/img]

[Jim Hand]

The exhaust components article I referenced is actually a summary of three different and separate exhaust component tests we have conducted. Each was fully authenticated and documented, and was initially published in High Performance Pontiac magazine. And on each we had exclusive use of the track so had strictly controlled test conditions and traction! And when trying to test or measure differences of one tenth of a second or less, the tests have to be made under the same weather and traction conditions. Otherwise, weather differences from one day to the next can cause a variance in times greater then the parts under test.

In theory, changing from a horrible exhaust system to an excellent one might change metering requirements. However, the minor changes gained would probably not be statistical significant for a test report. And when comparing performance mufflers or pipes, there is very little difference between them. So changing metering would just add another variable to the test.

It is possible that an X crossover might respond to slightly different metering, but the fact is that even with the metering optimized for the H crossover, which we had raced for several years, the X crossover was significantly quicker and faster. Jim Hand

[ January 28, 2002: Message edited by: Jim Hand ]</p>

[larry davis]

Mr. Hand, I appreciate your insightful advice!

What or how much power loss do you suspect by using the Dr. Gas 3" crossover & reducing to 2.5" before the up & overpipes to the transverse muffler? [img]/infopop/emoticons/icon_smile.gif[/img]

[Jim Hand]

Larry,
While running 2 1/2" mufflers, we tested 2 1/4" tailpipes against 3" tailpipes and saw almost no difference. As a result, I ran 2 1/2" mufflers and tailpipes with the 3" Dr. Gas system for years.

If you use a single transverse muffler that has 2.25" or 2.5" inlets, it is unlikely that the tailpipes will adversely affect performance. That is one of the unseen advantages of the X crossover - it allows each cylinder to see both sides of the dual exhaust system. That means that any restriction of the dual pipes or mufflers will be about half of what would be found with conventional duals. But again, the single muffler changes the equation - they just do not flow as well as conventional mufflers. I checked some numbers from our Silent Power CD project and here are several flow values:

Walker Super Turbo PN 17449, 2.5" - Flowed 70% of 2.5" open pipe.

Walker Ultra Flow PN 17288, 2.5" - Flowed 99% of open 2.5" pipe.

Flowmaster 42582, 2.5" Flowed 55% of open 2.5" pipe.

Jim Hand

[ January 28, 2002: Message edited by: Jim Hand ]</p>

[larry davis]

Jim, what about back pressure? I take it that it's not that important?

What type of power and decibels do those Walker ultra flows have?

My system will be 2.5" from just before the turn up over the axle-all the way back. [img]/infopop/emoticons/icon_smile.gif[/img]