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Old 09-30-2021, 09:06 PM
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Default PYPES Firebird system question

In doing the restoration on my 1974 Trans Am, one item I replaced was the complete exhaust system. I had originally bought the car in 1997 and the factory exhaust was shot. I bought a pair of Flowmaster mufflers, took the car to a local exhaust shop, and had a custom true dual exhaust system installed with an "H" pipe. The car seemed to pick up power and sounded great other than the drone it had at about 40-45 mph. I believe the system was a 2 1/2" system but I could be wrong and maybe it was a 2 1/4". Anyway, I bought the PYPES X pipe system for the car, the one with the crossover muffler that mounts behind the rear axle. This system is 2 1/2" mandrel bent.

I haven't driven the car much yet, but did drive it about 40 miles one day last week. It seems to me that it doesn't have the throttle response that it used to have with the old system or the performance. I don't have any hard numbers from a dyno to back this up, just going off how the car feels. Of course, I am comparing to what I remember from years ago. The car is completely stock other than the exhaust and has only 49k miles on it. It is a 400 4-speed. Any thoughts? Does and X pipe system actually lose low end torque?

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Old 10-06-2021, 09:56 AM
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hard to judge the seat of the pants feel without dyno or track tests to confirm. perception can play a big part, maybe the louder sound of the older system with mufflers under the floor made you think it was faster? just a guess but really hard to compare after a few years.

the X pipe & mandrel bent system should definitely make more power, engine masters & many other places say X pipes create more power & i would assume that means for torque too... but on a stock engine with manifolds the gains are probably minimal compared to a higher hp engine with headers that would benefit from it more.

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Old 10-07-2021, 10:49 AM
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Originally Posted by 78w72 View Post
hard to judge the seat of the pants feel without dyno or track tests to confirm. perception can play a big part, maybe the louder sound of the older system with mufflers under the floor made you think it was faster? just a guess but really hard to compare after a few years.

the X pipe & mandrel bent system should definitely make more power, engine masters & many other places say X pipes create more power & i would assume that means for torque too... but on a stock engine with manifolds the gains are probably minimal compared to a higher hp engine with headers that would benefit from it more.
What you are saying is certainly possible, plus, it has been so many years since I drove the car with the old exhaust. I will need to drive it some more. Maybe the carb needs rejetting now?

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Old 10-07-2021, 11:19 AM
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most say after big changes like that the carb needs calibrated, cant say how much or if that would help with what youre feeling though.

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Old 11-03-2021, 10:32 PM
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most say after big changes like that the carb needs calibrated, cant say how much or if that would help with what youre feeling though.
I suspect that my distributor is not getting vacuum advance. This would contribute to the car not feeling as peppy as it should. Test drive coming soon.

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Old 11-04-2021, 09:25 AM
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I did a bunch of track testing with this system, compared to the original Gardner system (which is pretty restrictive) A flowmaster transverse system, and the Pypes SGF70 transverse system.

On my bird simply switching to the flowmaster transverse system the car went from 14.0's to 13.70's and mph picked up from 99 to 102 best but would run 101+ mph occasionally with no other changes to the car.

I later switched to the Pypes setup and it would run a 13.6x on occasion but 70's were still common, and mph was consistently over 102. So there wasn't a bunch of difference between those 2 systems but Pypes seemed to be worth a pinch over the Flowmaster.

I've tweaked on the car here and there over the last few years, little things, and eventually have run a 13.10 at 104 mph with the same system.

There are cars in the PS drags that use this exact system running well into the 11 second zone so it has the capability of supporting some power. That transverse muffler is a straight through design on the inside with a little fiberglass packing. Basically just like the Pypes dual race pro mufflers or the Dynomax ultraflow construction.

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Old 11-09-2021, 07:29 PM
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Originally Posted by Formulajones View Post
I did a bunch of track testing with this system, compared to the original Gardner system (which is pretty restrictive) A flowmaster transverse system, and the Pypes SGF70 transverse system.

On my bird simply switching to the flowmaster transverse system the car went from 14.0's to 13.70's and mph picked up from 99 to 102 best but would run 101+ mph occasionally with no other changes to the car.

I later switched to the Pypes setup and it would run a 13.6x on occasion but 70's were still common, and mph was consistently over 102. So there wasn't a bunch of difference between those 2 systems but Pypes seemed to be worth a pinch over the Flowmaster.

I've tweaked on the car here and there over the last few years, little things, and eventually have run a 13.10 at 104 mph with the same system.

There are cars in the PS drags that use this exact system running well into the 11 second zone so it has the capability of supporting some power. That transverse muffler is a straight through design on the inside with a little fiberglass packing. Basically just like the Pypes dual race pro mufflers or the Dynomax ultraflow construction.

I suspect my car should run quite well with this PYPES system, even though the engine is otherwise stock. What I am finding is that the carb is too lean and the more efficient exhaust is making the problem worse. I spoke with Cliff R. on the phone. I have seated the air bleed screw on the Q-jet and will test drive to see if that takes care of the problem. If not, it will get new rods and jets for the primaries.

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Old 12-03-2021, 08:08 AM
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I just put this system on my wife’s car and am really disappointed with the sound. Even with long tubes it sounds like a stock TA. Hopefully it gets louder after it gets driven a bit. I will say the kit is very high quality and went together perfectly- just doesn’t sound near as good as the flowmasters I took off of it.

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Old 12-03-2021, 08:43 AM
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I think the sound and performance of the SGF70 transverse system is great. Just don't expect it to just bolt on and fit without a great deal of tweaking-especially on a 1977 model.

I had to re-jet the carb after the system installation due to the much higher flow of the system. Once that was done, the car responded well.

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Old 12-03-2021, 10:44 PM
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The sound quality with this system will change drastically depending on the engine combo and whether it has headers or manifolds.

On my Firebird, when I took the long tube headers off and went back to the RA exhaust manifolds, the exhaust actually got louder. The headers do a better job of scavenging and smoothed the exhaust tone quite a bit. It got a bit more "slappy" with the exhaust manifolds in place but still comfortable inside the car.

Here is my bird with stock 400 and this system, with RA manifolds in place.

https://youtu.be/uIFkggwDY-8

Same setup at the track inside and outside the car.

https://youtu.be/er1z7PpqsnY

https://youtu.be/XqEydRRRwqE

Same system on a 455 Pontiac, this one having RA exhaust manifolds. Sounds better on this Formula than it does on my 400 Formula.

https://youtu.be/AOqwz3QlO5k

Here's my other car with the same system. This is a SBC with headers and sounds quite a bit different.

https://youtu.be/47HgejCVbFs

Same system on our Z, and I did all kinds of different stuff with this one. Factory exhaust manifolds, then headers. Then did the supplied 2 1/2" tailpipes, then switched to factory 2" tailpipes which toned it down considerably, took some of the deep tone out of it.

https://youtu.be/5dTNw93VPEQ

https://youtu.be/IZ0HlEY7b74


Personally, for my taste, I think this system sounds better with a SBC in front of it but I have no complaints with the Pontiac.

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Old 12-04-2021, 09:28 AM
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I have the pipes cross flow on my 68 Firebird, and not really digging the sound. Very loud!!

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Old 12-04-2021, 09:58 AM
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Inside or outside the car?

I've found that by using factory hangers it greatly reduces any noise or drone inside the car. To take that even further, when I installed the 2" tailpipes on the Z for a stock appearance it knocked the sound down considerably, to the point where my wife now likes it, and she daily drives it. Personally I liked the sound better with 2 1/2" tailpipes but ultimately she's the one that has to be happy with it.

On my Firebird I ran the old Flowmaster Force II transverse system on it for years (not made anymore) and that was still much louder than the Pypes setup. Now the only transverse system Flowmaster makes is the American Thunder. Had that on a Nova and it was just down right obnoxious. Way too loud for me.

Outside the car, as far as Pypes goes, I've never liked their racepro mufflers when in a dual muffler configuration (like an A body). They are just all around loud and lack a refined sound. I always liked their streetpro's better. Unfortunately when using their transverse muffler it's only made in the racepro design, but I've never found it as loud as a dual muffler setup.

When it comes to transverse systems my other favorite is the Dynomax 89021. That one is quieter by a large margin and fitment is nice. It's aluminized (not stainless) but the best part is that it's under $300 for the kit. Mandrel bent 2 1/2" with an "H" cross over. Nice system for the money.

My go to mufflers these days are Dynomax.

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Old 12-04-2021, 01:41 PM
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I have the Pypes Violator under-car system on my 69 bird. It's LOUD. But does not drone which makes things a bit better.

The ground clearance isn't horrible, I actually have more issues at the header collector than I do the muffler and my car is very low.

I might swap out the mufflers for a Bassani. I've run those on mustangs for years and they are a great sounding muffler.

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Old 12-04-2021, 03:26 PM
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I ran Bassani on one of our 4th gen F-bodies for a while. They made a true dual exhaust system for those cars back then, one of the first to do so. Boy they sure made nice stuff, and I assume it's still great quality.

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