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It seems like as the car gets faster/more aggressive, it doesn't sound as good- it's gone from what used to be a rich, deep muscle car sound to a raspy metallic sound with a lot of other noises. I have a cutout on the car, and in most cases, you'll hear it closed, and I want to keep the ability to make it relatively quiet so I can close it and not attract unwanted attention at times (there's a lot of "your car is loud, you must have been the one racing," around here), but opening it just gets more raspy and metallic sounding I tend to like cruising with the cutout cracked but not wide open, just to add a little auditory feedback to what it's doing. Interestingly, it has a fairly large cam and large intake ports for a 305, but in these clips, it's idling at 600 rpm, and there really isn't much lope to it.
'87 Trans Am
Stock bottom end
4/7 swap cam/short travel lifters/over .600" lift
Heavily modified mid-90s aluminum LT1 heads
80s Victor Jr converted to FI
LS truck throttle body
MegaSquirt ECM
Headman headers, 3" exhaust with Dynomax Ultraflow welded (has a small rust hole in it, roughly 1/4 x 1/2") and a cutout mounted in front of the axle.
Last edited by 83 Crossfire TA; May 18, 2025 at 05:50 AM.
FWIW, the intake is VERY noisy, when it first starts up it almost sounds like a metallic ringing (you can hear it in the beginning of the first video clip in the linked video) which can sometimes sound cyclic if the tune is nudging the timing up to maintain the idle speed, and once it warms up the sound goes sort of "breathy," as if someone is breathing hard through their nose, it's very noticabledurring the third/last clip in the video.
I agree, I don't think that most people could tell a CFI corvette from a TPI corvette by sound, but for sure you could tell a CFI f-body from a 305 or 350 TPI f-body. Even more interesting, when I bought my 83 it had a "factory replacement," style Walker/Dynomax exhaust (only available in the later, crossflow muffler style muffler) and it still sounded more like the twin muffler early cars then a TPI car (only a hair quieter then the twin muffler setup). Why are they so different???
2 friends of mine had an 83 and an 84, one an LG4 and the other an L69, and we did all 3 cars at the same time (exhaust at one point, headers at another point, suspension...) and we added an early TPI car to the mix eventually. Mine ended up Headman 3/4 length (most call them shortie but they're not like mustang or corvette shorties), dual cats, flowmaster y, 3" open pipes I described earlier. the other 83 got ebrock TES + the early dynomax cat back (single 3" muffler and single 3" tailpipe), the 84 got Hooker 3/4 headers, later dynomax cat back (essentially mild steel TTL), and the TPI got edlebrock TES + SLP TTL. My CFI remained distinctly crossfire sounding, the other 3 were pretty hard to tell apart, I remember that the TPI car ended up quieter than the rest.
I kind of wonder if part of the CFI sound is compression and cam. They were advertised as having 9.8:1 with iron heads, and the cam was similar to the later TPI cam with less LSA.
This is for sure a thing. There used to be a knockoff of the Hooker Aerochamber that I put on my '92 K1500 2 door blazer. That had an interesting exhaust- driver's side Y into the passenger side, from there straight back to the muffler (cat went in that pipe but I removed it), straight back out of the muffler, 1 bend to the outlet. That one sounded BLAAAAA, almost like a bad open exhaust (muffler fell off) on axis with the tailpipe, and sounded deep, Aerochamber like off axis.
I'm not sure what to make of that, I mean the f-body shorter headers are closer to the corvette then the rest, for sure on the driver's side where the collector is typically below 3/5 and against the back of the K member. I guess they don't have the symmetry of the c4 corvette headers.
Mustangs sound pretty much the same with snake's nest equal-length headers as well as the standard non-equal ones. They don't sound that different outside the car with dumps before the axles either
Sorry, yes, the primary pipe lengths, or distance from head port to collector is what I was getting at with reference to the location of the collector. The combination of the syncopated firing pulses on each side, with the primary pipe length culminates in a pulse/rhythm/tone, that could set up the basis for that car's exhaust sound in general. I think.
I have no idea why the CFi could have sounded better. Could have been cam and compression but there has to have been other combos since, that had similar cam compression that don't have "that sound".
I think you car needs another muff in the pipline somewhere to knock down the loudest parts. Then, I wonder what would happen if you split it like the early OEM system, but used 2" or 2.5, rather than 1.5? Or what ever it was back then? and had each pipe go through a "turbo" muffler. I know those don't flow great, but for sound....I wonder how that would sound on your car.
What is the timing at idle? I know it moves, but generally, what is it?
It's high, in the low 20's. This MS has been on this thing for a long time, before some of the current settings existed like all the current options to tune idle. Back in the day I had the idle set to 800, and then had a column in the timing table at 800 where the timing was the lowest, then another column below it at 600rpm with anything hear an idle MAP a few degrees higher so if idle drops below the set point the timing would catch it. I just recently got it running and messed with all the idle tuning stuff, lowered the idle to 600 (it even idles OK at 500) where it sounds tamer, and flattened out the timing curve but it's still high.
What's the exhaust right now?
Um, in the first post, in the video description, in the last thread... but again, with the rest of the info: '87 Trans Am Stock bottom end 4/7 swap cam/short travel lifters/over .600" lift Heavily modified mid-90s aluminum LT1 heads 80s Victor Jr converted to FI LS truck throttle body MegaSquirt ECM Headman headers, 3" exhaust with Dynomax Ultraflow welded (has a small rust hole in it, roughly 1/4 x 1/2"), turndown at the bumper and a cutout mounted in front of the axle.
Originally Posted by Tom 400 CFI
I think you car needs another muff in the pipline somewhere to knock down the loudest parts.
I'm curious what exactly you have in mind there. My brain goes to putting a bullet in the intermediate pipe,
but I don't really have room, 3.5" driveshaft, crazy overbuilt TA and no ground clearance.
Then, I wonder what would happen if you split it like the early OEM system, but used 2" or 2.5, rather than 1.5? Or what ever it was back then? and had each pipe go through a "turbo" muffler. I know those don't flow great, but for sound....I wonder how that would sound on your car.
The 2 pieces in the middle are the Y pipe and the intermediate pipe, that connected to the Y at the bottom that split into 2 smaller pipes going up over the axle, and on the other side the 2 smaller pipes went into the center pipe which went into the mufflers on either side and out the tailpipes.
For those of you that don't know, the early 3rd gens had a crazy factory exhaust with small dual mufflers, This is the only picture that I could find. The 2 pieces in the middle are the Y pipe and the intermediate pipe, that connected to the Y at the bottom that split into 2 smaller pipes going up over the axle, and on the other side the 2 smaller pipes went into the center pipe which went into the mufflers on either side and out the tailpipes.
I actually had something similar on my '83 CFI car but I installed headers, made a dual 2.5" cat y pipe, 3" OTA pipe, from there it looped around to the center of a 3" U-shaped pair of 3" tailpipes
Something like this sounded great, but wouldn't pass emissions. I could never get the flow the same from one side to the other, and if one pipe measured lower than the other, they assumed that you were trying to pump air into the exhaust to lower the emissions, and you automatically failed. Of course, this was in 1991, when the car still needed to pass emissions.
Last edited by 83 Crossfire TA; May 19, 2025 at 02:52 AM.
Can someone tell me what is going on with the image attachments? I drop them in, they let me add text, but they won't display in the thread. If you highlight the URL you can open it in another tab and if I go to edit, I can see my pics, they just don't display in the thread. this is like the 3rd or 4th time that it's happened to me recently and is really freaking annoying
Edit: I posted about it in the site boards problems section, and the moderator seems to think it fixed itself. I may try to add something more.
Last edited by 83 Crossfire TA; May 20, 2025 at 05:02 AM.
Even weirder, I can see them if I quote the text, I wonder if they will show if I submit this:
Originally Posted by 83 Crossfire TA
It's high, in the low 20's. This MS has been on this thing for a long time, before some of the current settings existed like all the current options to tune idle. Back in the day I had the idle set to 800, and then had a column in the timing table at 800 where the timing was the lowest, then another column below it at 600rpm with anything hear an idle MAP a few degrees higher so if idle drops below the set point the timing would catch it. I just recently got it running and messed with all the idle tuning stuff, lowered the idle to 600 (it even idles OK at 500) where it sounds tamer, and flattened out the timing curve but it's still high.
Um, in the first post, in the video description, in the last thread... but again, with the rest of the info: '87 Trans Am Stock bottom end 4/7 swap cam/short travel lifters/over .600" lift Heavily modified mid-90s aluminum LT1 heads 80s Victor Jr converted to FI LS truck throttle body MegaSquirt ECM Headman headers, 3" exhaust with Dynomax Ultraflow welded (has a small rust hole in it, roughly 1/4 x 1/2"), turndown at the bumper and a cutout mounted in front of the axle.
I'm curious what exactly you have in mind there. My brain goes to putting a bullet in the intermediate pipe,
but I don't really have room, 3.5" driveshaft, crazy overbuilt TA and no ground clearance.
[img alt="For those of you that dont know, the early 3rd gens had a crazy factory exhaust with small dual mufflers, this is the only picture that I could find.
The 2 pieces in the middle are the Y pipe and the intermediate pipe, that connected to the Y at the bottom that split into 2 smaller pipes going up over the axle, and on the other side the 2 smaller pipes went into the center pipe which went into the mufflers on either side and out the tailpipes."]https://cimg2.ibsrv.net/gimg/www.thirdgen.org-vbulletin/1920x1275/image_5794f29915f0d4cc70b4a5c8671e21573c88e692.png[/img] For those of you that don't know, the early 3rd gens had a crazy factory exhaust with small dual mufflers, This is the only picture that I could find. The 2 pieces in the middle are the Y pipe and the intermediate pipe, that connected to the Y at the bottom that split into 2 smaller pipes going up over the axle, and on the other side the 2 smaller pipes went into the center pipe which went into the mufflers on either side and out the tailpipes.
I actually had something similar on my '83 CFI car but I installed headers, made a dual 2.5" cat y pipe, 3" OTA pipe, from there it looped around to the center of a 3" U-shaped pair of 3" tailpipes
[img alt="Something like this, this sounded great but wouldnt pass emissions, I could never get the flow the same from one side to the other and if one pipe measured lower then the other they assumed that you were trying to pump air into the exhaust to lower the emissions and you automatically failed.
Of course, this was in 1991, when the car still needed to pass emissions."]https://cimg9.ibsrv.net/gimg/www.thirdgen.org-vbulletin/1360x1613/image_62c31b062a5e9933c6f89ff45d519aa13ad21862.png[/img] Something like this sounded great, but wouldn't pass emissions. I could never get the flow the same from one side to the other, and if one pipe measured lower than the other, they assumed that you were trying to pump air into the exhaust to lower the emissions, and you automatically failed. Of course, this was in 1991, when the car still needed to pass emissions.
That said, I'm not so much about too loud/or too quiet when I'm driving, I guess I've been doing this longer then most of you but I haven't gotten to the point where I want my stuff quiet, but I tend to go to the gym and other places late and I've been known to work on the car before dawn/early because I hate hot weather, so like that I can quiet it down for those reasons, not to annoy my neighbors (they tend to be decent and they wouldn't say anything so I don't want to be a problem).
Anyway, besides that, I stress more about performance loss and how badass it sounds rather than how loud it is overall. I personally feel like it sounds OK, not good but OK, with the cutout closed, and the cutout open definitely gets attention but I think it sounds tinny. I haven't tested it in a while, but last time I did it didn't run faster with it open, so I wasn't too concerned, but since I noticed that the current tune revs differently/slower with it open I'm wondering if that's still the case.
Since I've had the Ultraflow Welded that is on there since some time in the '90s (it's moved from car to car) and it has a hole in the case (which I have previously welded), I figured that I'd just replace it with a similar one with the next larger case which according to their flow numbers shouldn't be a restriction. I also have a Hooker Aerochamber in the same size and configuration that I could put in there. I suspect that it will sound better, possibly be louder, and possibly be more of a restriction. Other things in my stockpile:
Whatever muffler comes in Magnaflow's crossflow cat back for 3rd/4th gens,
I'm pretty sure I have the muffler and pipes from a 4th gen (that might be interesting with the cutout, I'd expect it to be quieter then the U W muffler but I'm not positive, I know that I've tested them on my '97 and wasn't able to show a power difference on a car running N2O and low 11's @ 117 (this car should be about 1 second slower, but I have a spare 15lb bottle sitting around and it's built for a turbo so that could change at the drop of a hat). The interesting thing about 4th gen cat backs is that the taillpipes came out about 2.5-3" to the driver's side of center. The cars that had exposed taipipes all had cast tips that had their inlets offset to one side. I'm betting that I have both Firebird and WS6 tips floating around.
I think I have an actual SLP TTL muffler and tailpipes, they're probably in roughish shape, I know the intermediate pipe rotted out on that one (yeah, they're 409 stainless but someone did some welding on it with mild steel wire and rusted and broke everywhere where it was welded)
I have the prototype for the Spintech 4" in, dual 3" out muffler that Mufflex offered as an option later with the 4" cat back (long story, their original cat back had a single 4" tailpipe on the driver's side and I wanted a crossflow muffler at the time, I talked to spintech, they asked me for dimensions from the stock muffler, they sent me what they made to test fit it)
At some point I wanted to try putting a Y in the back an running a small muffer on each side, I know that I have a pair of polished 3" stainless bullets/short glasspacks (don't remember the brand) that I intended to try in that configuration, I'm guessing that this would be too loud with the current engine configuration, I intended to put that on after adding a turbo
I have various "regular mufflers," mostly in 2.25, 2.5, and 3" sizes, probably the most interesting would be I think I have a pair of large case dynomax "Hemi Super Turbo mufflers," (the "hemi" versions have 3" tubes inside, but I know that those flow significantly less than the Dynomax ultraflow welded mufflers)
I'm sure I have other stuff around, and clearly, with a collection like that, I'd be willing to buy other stuff.
I don't have a clear idea what I want to try next... I know that wonder what something laid out like the old borla cat back which had it's driver's side tailpipes go through the muffler and the passenger side bypassed it and it had removable plates that had different size holes so you could "tune" it, I'd replace that with an electric cutout (lets see if this works):
I've wondered if this kind of setup with maybe a glasspack or bullet behind the cutout might sound better, of course i'd miss WIDE open volume that I have now...
and had each pipe go through a "turbo" muffler. I know those don't flow great, but for sound....I wonder how that would sound on your car.
