What rear mufflers are you running if not stock?

[Last triumph]

My stock '81 has a true dual de-cat 2.5 system with stock rear mufflers and to be honest, the sound is just too quiet and un-impressive. There's more fan and intake noise than exhaust, or at least that's how it sounds.

I'd like to replace the rear mufflers with something that are far louder and deeper but am struggling to find something appropriate.

I'm looking to achieve something along the lines of a TVR Griffith in terms of absolute minimum volume and tone, but would like it a little louder than that if I'm honest.

To give you an idea, if stock is 1 out of 10 and straight pipes are a 10 in terms of noise level, I guess I'm looking for a 6-7 - something loud and "wow, listen to how glorious that sounds" without being as obnoxious, anti-social and un-refined as straight pipes.

I considered Dynomas race bullets, but have come to the conclusion that they're just a bit too loud.

I don't like or want the tinny Flowmaster 40s (nor to I like the restrictive design).

Magnaflow sound a bit quiet from what I've heard on Youtube clips.

I ran cherry bombs on a '80 once which was about the right volume, although louder would've been fine, but their tone was a bit flat.

Open to suggestions and ideas.

The Borla ATAKs sound good but very expensive.

 

[Chuffer]

My 1980 came with 2.5 inch system and cat with Supertrapp muffler / tail pipes . I thought it sounded great at the time but have now taken cat off and it sounds even better . Loud enough for me me , but too loud for the wife . It has a nice woofly crackle on overrun when decelerating from speed and gets good comments from people who appreciate a V8 soundtrack .

 

[kentvette]

We had the stainless system on our car built specifically for it, via a deal that Tom Falconer did with a company in Devon (Pipers, now long gone I think) that he was hoping to use for limited production of exhausts. It was a two day process and when it came to the boxes, the boss was very particular about asking me exactly what sort of sound I was after. I told him I wanted a nice rumble at idle, and a bit of a "roar' on acceleration etc, but not overly loud on a long run. That all seemed a bit hard to achieve to me, but they managed it, and we were thrilled when we drove the car away and have been very happy ever since - which is now at least 20 years later!

What I'm getting at is, that if you can find a specialist exhaust builder they could probably get the sound you want built into a box.

 

[Roscobbc]

'Absorbsion tube' mufflers like Magnaflow and Cherry Bombs use a simple can packed with a sound deadening material. The central 'straight through' tube is perforated with multiple holes. Cheery Bombs and some cheaper mufflers use glass fibre wadding as the sound deadening medium. This is fine for a short while but gradually degrades with oil and soot from the exhaust and in time will loose much of it effectiveness (and sound horrible). Better quality mufflers will use alternative wadding material (ceramic wool, stainless wool or layers of each) and last far longer. They will all get noisier with use........you just have to be prepared to wait or do loads of miles to 'soot' them up a bit. The design of absorbsion type mufflers will generally mean a reasonably quiet (but pleasant) sound on a light throttle and a far more fruity sound when stepping on the loud pedal.
If you are prepared to do a bit of measuring and calculation take a look at Jetex mufflers - these are made in Sweden I believe, not cheap but available in mild or stainless steel in different lengths and shapes with pipe sizes up to 4" diameter (you'll only need 2.5" maximum). The longer the better - measure-up your existing mufflers and perhap select the nearest suitable size........... Jetex Exhausts Ltd – Oval silencer box [HEAVY] [2.5 inch] [stainless steel] – H=140mm / W=220mm / L=500mm / Volume=9.4L - I've used these on a number of cars over the years and they seem to last for ever.

 

[Last triumph]

'Absorbsion tube' mufflers like Magnaflow and Cherry Bombs use a simple can packed with a sound deadening material. The central 'straight through' tube is perforated with multiple holes. Cheery Bombs and some cheaper mufflers use glass fibre wadding as the sound deadening medium. This is fine for a short while but gradually degrades with oil and soot from the exhaust and in time will loose much of it effectiveness (and sound horrible). Better quality mufflers will use alternative wadding material (ceramic wool, stainless wool or layers of each) and last far longer. They will all get noisier with use........you just have to be prepared to wait or do loads of miles to 'soot' them up a bit. The design of absorbsion type mufflers will generally mean a reasonably quiet (but pleasant) sound on a light throttle and a far more fruity sound when stepping on the loud pedal.
If you are prepared to do a bit of measuring and calculation take a look at Jetex mufflers - these are made in Sweden I believe, not cheap but available in mild or stainless steel in different lengths and shapes with pipe sizes up to 4" diameter (you'll only need 2.5" maximum). The longer the better - measure-up your existing mufflers and perhap select the nearest suitable size........... Jetex Exhausts Ltd – Oval silencer box [HEAVY] [2.5 inch] [stainless steel] – H=140mm / W=220mm / L=500mm / Volume=9.4L - I've used these on a number of cars over the years and they seem to last for ever.

Thanks, will have a look. One question, do they sound utterly gorgeous and bad-ass, without me sounding like a 13 year old. TVR Griffith volume and 'wow' is my absolutely minimum base line. More wow and a bit louder even better.

The cherry's I have on the '80 back in the day had a bit too much fffft-fffft-fffft noise to them - not very 'clear', whereas Flowmasters sound like a rock in a washing machine at idle if you like that thing.

I'm still tempted with the Dynomax bullets, as ultimately, I want it to sound like this.... (35 secs - 45 secs) pretty much nails my level of desired ''bad-ass'.

For the record, the car will only ever be driven on short local trips for a bit of fun when the roads are clear and dry. Long journeys, passenger conversations, the ability to hear the 'crackle-master 2000' stereo are not factors.

 

[Last triumph]

We had the stainless system on our car built specifically for it, via a deal that Tom Falconer did with a company in Devon (Pipers, now long gone I think) that he was hoping to use for limited production of exhausts. It was a two day process and when it came to the boxes, the boss was very particular about asking me exactly what sort of sound I was after. I told him I wanted a nice rumble at idle, and a bit of a "roar' on acceleration etc, but not overly loud on a long run. That all seemed a bit hard to achieve to me, but they managed it, and we were thrilled when we drove the car away and have been very happy ever since - which is now at least 20 years later!

What I'm getting at is, that if you can find a specialist exhaust builder they could probably get the sound you want built into a box.

Thanks - the system on there is pretty new and I'm not keen on the expense of a custom designed system from scratch compared to finding a pair of rear mufflers to replace in an hour that gets me in the ball park. Don't get me wrong, if I had the budget I would, but for now just mufflers will have to do.

 

[Mr. Cricket]

Happy with the cherry bombs on the red LT-1 but sometimes I get to thinking they're too loud.

Glass Packs on the yellow one are not as loud as the cherry bombs but still pack quite a rumble.

Pop 'round and have a listen

 

[Roscobbc]

The Jetex mufflers I used had a softer tone on idle - softer than the stock baffled mufflers in fact. On a light throttle and cruising they would remain quite 'soft' - getting louder one you stepped on the gas. IMHO sound of car on video was a little bit 'too much' and typical of the Cherry Bomb sound.
Generally the larger the diameter of exhaust system the deeper the sound. Stainless steel will sound a bit different too - a bit metallic sounding.

 

[teamzr1]

Hard to tell via a video what exhaust sounds of a muffler type really are and also what the weather temps are

Using bullet glass pack type on my 1999 C5

Cold weather and cold start

From a dead stop

Part throttle

WOT

Testing is the best part of exhaust designs

When wanting to piss off the ole lady and those living within a block of you
112 Dba



3 inch diameter pipe from header collectors to exhaust tips

 

[hurtzcsa]

A mate has flow master replicas on he`s corvette. the car sounds exactly the same as a car with flow masters but a lot cheaper. they are about £120 the pair. he got them of Michael Pusey

 

[hurtzcsa]

not he`s car but this is how it sounds

 

[Last triumph]

not he`s car but this is how it sounds

Thanks, but that's a bit quiet for my tastes.
The C5 video further up is more what I'm after I think. Maybe the 12" bullets with down turned (stock style) tail pipes are the answer?

 

[teamzr1]

Thanks, but that's a bit quiet for my tastes.
The C5 video further up is more what I'm after I think. Maybe the 12" bullets with down turned (stock style) tail pipes are the answer?

I spend many months in testing different designs and metal types as how sound can change as to design.
Including if a stock H pipe in mid-pipe to my final design of using 3 inch X-pipe in place of the CATs

Team ZR-1 Exhaust Design & Testing

Final outcome of exhaust sound changes depending on using mid steel pipe to stainless steel
Size of pipe from exhaust ports, where the H or X pipe is installed to position of exit tips and direction they are pointed
As photo, I showed above when tips were placed by the tranny and pointed downward, HOLD your ears as in my case using 3 inch pipe from the 3-inch header collectors to even the inlet and outlet of mufflers also 3 inches and the sound bounced off the ground, then back up and bounced off underside of the Corvette
I used a dBa sound meter for all testing and even found that if sticking the tips straight back and placing them past ass end helped lower the dBa from 112 when tips were under tranny to 84 dBa (inside cabin) when tips ended further out
Even a difference if I used a single or double wall exhaust tips and if I used 3 inches or 4 inch tips

If wanting to balance the sound, add a H pipe mid-stream
Want better skavaging and exhaust pulses use an X-pipe close to exhaust manifold or collector of headers

Here in the USA, federal law limits at certain dBa (Max allowed is 94 dBa measured at 2 feet from tip at right angle)
I am big on noise levels as screwed by left ear up from racing with side exhaust with little mufflers, no side windows and even with helmet on
I should have also used earplugs :-(

Decibel Exposure Time Guidelines

Accepted standards for recommended permissible exposure time for continuous time weighted average noise, according to NIOSH and CDC, 2002. For every 3 dBs over 85dB, the permissible exposure time before possible damage can occur is cut in half.

Continuous dB Permissible Exposure Time

85 db 8 hours
88 dB 4 hours
91 db 2 hours
94 db 1 hour
97 db 30 minutes
100 db 15 minutes
103 db 7.5 minutes
106 dB 3.75 min (< 4min)
109 dB 1.875 min (< 2min)
112 dB .9375 min (~1 min)
115 dB .46875 min (~30 sec)



Do not do this if you want to keep your brain in once piece

 

[Last triumph]

Love stuff like that, thanks for posting.

The only element of my system I want to touch is the rear mufflers, so I have 2.5" to play with and 19" total to play in either side of the spare wheel carrier.

I get, (mostly) understand and appreciate (most) of the theory, but ultimately I'm simply looking to improve the sound of my pretty stock '81 with nothing more than swapping out the stock style mufflers on the no-cat, 2.5" true dual set up.

So far, from the what seems like endless Youtube clips I've heard, it's a toss up between 12" Dynomax race bullets (perhaps too loud) and 14" Dynomax Ultra Flo Round (perhaps a bit too quiet).

From what I've heard, these straight through Dynomax mufflers appear to be closest to the combination of deep below vs savage roar, without the 'rock in a washing' machine sound of Flowmasters (or the flow restriction).

 

[teamzr1]

If you have a decent exhaust shop near you, see if they can experiment with you in putting in the mid-pipe an H-pipe with what mufflers you decide on
Listen to that and then swap the H with an X-pipe and listen to that
H pipe will balance the sound and an X-pipe will boost the low end torque a bit

I went with an X-pipe close to the engine and that helps pull the exhaust gases out of cylinders, so the next firing is full of clean air/fuel which is a better cold charge.

 

[Last triumph]

If you have a decent exhaust shop near you, see if they can experiment with you in putting in the mid-pipe an H-pipe with what mufflers you decide on
Listen to that and then swap the H with an X-pipe and listen to that
H pipe will balance the sound and an X-pipe will boost the low end torque a bit

I went with an X-pipe close to the engine and that helps pull the exhaust gases out of cylinders, so the next firing is full of clean air/fuel which is a better cold charge.

View attachment 13795

We're pretty useless here in the UK and don't have these types of exhaust places readily available for such collaborative experimentation. That's not to say they don't exist, just not in my location (or budget).

Like I say, it's a rear muffler replacement exercise and nothing more at this stage.

 

[teamzr1]

Have you seen any of these mufflers ?
Many different types

Ebay - Mufflers

 

[Last triumph]

Have you seen any of these mufflers ?
Many different types

Ebay - Mufflers

Yep - but the question is how do they sound / perform, and for that, I prefer to go on sound clips and recommendation rather than buy on a leap of faith in the hope they sound good and perform well.

 

[Roscobbc]

This is with custom built 3" stainless 'X' pipe system and absorbsion tube mufflers leading from headers. Phone doesn't pick-up low frequency too well - its reasonably quiet up to 3000 rpm and then gets increasingly louder.

 

[Last triumph]

This is with custom built 3" stainless 'X' pipe system and absorbsion tube mufflers leading from headers. Phone doesn't pick-up low frequency too well - its reasonably quiet up to 3000 rpm and then gets increasingly louder.

Lovely looking car, but I'd be looking to be a fair bit louder and more aggressive sounding than that.