Exhaust exhaust tone/volume w/swap?

[crucifyd]

89 GT bone stock less flowmaster cat back....

what difference, if any, would swapping these factory parts for an aftermarket
unit make as far as exhaust tone / volume?

1. headers

2. crossover pipe

 

[AeroCoupe]

Depends on shorties or long tubes and h or x pipe and whether or not you are going to run cats. What diameter exhaust?

 

[crucifyd]

sorry I wasn't clear. it's all stock from headers to cats then Flowmaster American Thunder cat back system...

the AT kit is 2 1/2". I actually have no idea what the factory parts are, I thought I recalled reading that it was 2 1/4"(?)

 

[Mustang5L5]

Headers, prob little to none of going to shorty headers.

Stock h-pipe to aftermarket will be much more dramatic, especially if the off-road variety. Will be much louder

 

[AeroCoupe]

I would say that there would be a gain with shorties if the rest of the system is all 2-1/2". The factory manifolds are not that great. I will say that I did do a little surgery to my BBK equal length shorties in that I removed the weld bead on the inside of the primary tubes where they are welded to the head flange and I opened up the fire cone as it was 2-1/8". Not sure if that made any difference but when I had the car torn apart to put the 331 in it I figured it was a good way to kill more of my time.

 

[crucifyd]

Stock h-pipe to aftermarket will be much more dramatic, especially if the off-road variety. Will be much louder

swapping the h-pipe out would mean replacing or losing the cats, correct?

 

[AeroCoupe]

Correct. The stock cats are 2-1/4" inlet and outlet so they would be a choke point. You can order an off road H or X and then install cats in it. That is what I did when I lived in Houston and it passed the sniffer test with zero issues.

 

[85GTStangGuy]

..... and I opened up the fire cone as it was 2-1/8". .....

Not quite understanding this.... what exactly did you do?

 

[AeroCoupe]

I did this over the winter when the 331 was being built so I had idle time. BBK welded the primaries to the header flanges on the inside which I am assuming was to make room for the header bolts. Some pictures of what I started with and what I ended up with:

Here is the side by side comparison, I had one header completely ported and the other is as is from BBK

Here is the one ported by itself

Its kind hard to see what I am talking about in the first two pictures so I zoomed in and just concentrated the pictures on one port.

Here is the unported picture

Here is the ported picture

You can see that there was a pretty good obstruction in each one. I then moved to the collector area which is what most call a fire cone due to the type of connection or at least that is what I remember it being called. Measured both and they were right at 2-1/8" on ID. Searched around on the net and mostly the Corral and found that this is nothing new and that JBA is about the only one with a true or close to 2.5" ID. I took a black Sharpie and ran a 1/8" thick line around the opening of the collector where the X-Pipe slides on and proceeded to open them up. I was a bit leery of 2.5" as I wanted to make good and sure these things sealed back up right. Nothing worse than an exhaust leak....tick, tick, tick...annoying as all hell. Here are some pictures of what it looked like before and after.

Stock BBK collector opening (you can see the black Sharpie outline):

After I marked the lip with a Sharpie and used a 4" grinder to knock the lip off of it. You can see the wide, flat edge that is shiny:

And the finished product measuring 2-3/8" ID. Not that it would gain me 15 hp or anything but I just could not leave it alone:

Here they are side by side so you can really see the difference:

 

[General karthief]

After some research and talking to a header expert I'm toy'n with a slip fit type collector doing away with the restrictive ball socket connector.
Not sure yet.

 

[2000xp8]

Switching to an offroad pipe with flowmasters is going to make the car loud, very loud. Probably drone horribly too.

Personally i would buy a high end catted X pipe.

 

[keel]

I have BBK long tube headers and a catless x-pipe and the car is actually pretty quiet at low RPM and idle but really opens up and screams at wide open throttle, which I really like. It sounds a lot more sporty in my opinion compared to the kind of truck-ish sound of the stock exhaust system with the shorty headers and h-pipe. This is with magna-flow street mufflers though. From what I understand the flowmasters are a lot louder and can drone pretty badly.
Highly recommend long tube headers from a sound perspective but they can be a pain in the butt to install and work around.

 

[AeroCoupe]

The exhaust on the Coupe is pretty mild at idle and part throttle but WOT it will rip the tin off a shop. I said something about it to the tuner and he told me no big deal. He came and got me after about the 4th full pull (few part throttle pulls before them to get the fuel fattened up) to locate the MSD and remove the 6,000 rpm pill and let me know that my car was loud and everyone in the shop said it was loud. Firm believer that the X-pipe makes the exhaust tone for lack of better words "rippy" up top unlike and H-pipe. Anyhow, would not change a thing on mine as l really like the access with the shorties and F battling one piece long tubes. T-Bird has slip collectors so and each primary bolts to the head so they can be snaked through the k-member so they are fairly easy to install and remove.

 

[keel]

Firm believer that the X-pipe makes the exhaust tone for lack of better words "rippy" up top unlike and H-pipe.

Agreed, I switched from an offroad h-pipe to an x-pipe and I really noticed the difference high in the rev range. The h sounded more muscular at low RPM but died down a little at high RPM, where the x was just the opposite, was noticeably quieter at low RPM compared to the h but much louder and more exotic sounding at high RPM. The h also has kind of a rougher sound to it. It was cool to see how much of a difference could be made just by switching that one part of the exhaust.
The long tubes are certainly a battle, I currently have the trans out of my car and I had to unbolt the headers in order to pull the bell housing off because otherwise it gets trapped in there between the headers and the trans tunnel.

 

[85GTStangGuy]

@AeroCoupe - Thanks for the detailed explanation and great, close-up pics. Well documented! Answered all my questions on what your process was.

I then moved to the collector area which is what most call a fire cone due to the type of connection or at least that is what I remember it being called.

You're correct in referring to it as the collector.
"Firecone" is actually the trademarked name of JBA for their patented collector technology. Basically, it's a pyramid shaped piece on the inside of the collector, welded in where all 4 pipes come together. The engineering behind it makes sense to me.

From the JBA Header page:
"With ............ proprietary technology, like the JBA Firecone collector JBA shorty
headers have the capacity to produce more power than any other shorty headers on the market."

The engineering theory behind it is explained in the last article in the Tech Resources section on the link below (note: it requires downloading the article to read it):

Headers

Looking for an edge in performance? Look no further than high-performance exhaust headers. At JBA, we offer heavy-duty stainless steel headers for late model cars and trucks that produce massive power gains. Doug's Headers has been a name respected since the 1960s and remains one of today’s...

pertronixbrands.com

 

[nickyb]

swapping the h-pipe out would mean replacing or losing the cats, correct?

If you gotta pass sniffer smog test then get mid pipe with cats.
I don't know if you like it loud but , I had a catted h pipe with flowmeter and it was ok, then I got a deal on used loudmouth Cat back and I now have BB K sorties , BB K catted x pipe with loudmouth catback. It's the right amount of loud for my daily driven fox.

 

[crucifyd]

If you gotta pass sniffer smog test then get mid pipe with cats.
I don't know if you like it loud but , I had a catted h pipe with flowmeter and it was ok, then I got a deal on used loudmouth Cat back and I now have BB K sorties , BB K catted x pipe with loudmouth catback. It's the right amount of loud for my daily driven fox.

no sniff needed ... just as she was passing the age for required sniff test (25 years) the state stopped them all together "because our emissions program has made such a difference" ***eyeroll***

I like it loud...

just to make sure, you're saying the loudmouth setup is significantly louder?

 

[nickyb]

no sniff needed ... just as she was passing the age for required sniff test (25 years) the state stopped them all together "because our emissions program has made such a difference" ***eyeroll***

I like it loud...

just to make sure, you're saying the loudmouth setup is significantly louder?

Oh yes , hence the name loudmouth.
Quiet while at a stop light next to p.o. p.o. , then as rpms rise so does the sound

 

[87cooper]

Great info from all!