1968 427/390 with hotter cam (from PO)
Doug's headers/sidepipes

I made custom inserts - Magnaflows with 2.5" pipe and adapters.
I wrapped them with header tape and put them in.


They concept worked and the side-pipes do not burn BUT it is too loud.

So.... I want a fun daily summer driver. I do not want to put super restrictive inserts in.
Are all straight through inserts going to be real loud?
Are the spiral inserts better?
Am a chasing a fantasy and need to come to grips with the fact that header/side-pipes are loud?




I am considering going back to standard rear exhaust.

Thoughts?

Thanks.....

 

I used inserts from Car Chemistry on the side pipes for my 66. It cut the sound and raspy sound down. Jerry

 

Non-restrictive side pipes are loud. Pick one or the other.

 

I managed to quieten down some sweet thunder inserts that go into a 4 inch side pipe At 2.5 inch straight through they sounded great but we realised that we were shouting at each other while standing next to it idling. By drilling lots and lots of holes in the centre chamber and then wrapping that with muffler fibreglass wrap and then steel wool , the sound did reduce .
Just looking at yours , well your muffler is too small length wise and it being almost the same dia. As your pipe , you have no room to do any more .

The sweet thunder inserts are narrower in the middle and flare out each end to fit the 4 inch pipe and are almost the full length as well.So they were a better design to modify imo.

Also summit sell an insert cone shaped , that knocks a few decibels off and is said to not reduce exhaust flow. I put some of those in the front cone of the muffler and that helped a bit more as well.

 

Ear plugs or loud radio.

Or in my case diminished hearing from youthful craziness....so I leave the hearing aids out.

All kidding aside.....do a search with the advance search function.
Several members have posted their solutions.

Good luck.

Keep in mind that sidepipes are not as functional as straight back headers so there is a trade off there to begin with.
Restricting the flow for reduced noise vs less restriction for more hp/torque is always going to be a trade off.
I have side pipe headers for my project.

Post up your results....

 

I use dougs reverse flow muffler inserts for my sidepipes. I love the sound. Great low rumble that doesnt wake all my neighbors up with I drive to work in the early morning and can certainly hear it when I hit the gas. Cruising on freeway in overdrive doesnt make me deaf either.

 

How are the factory 69 side pipes compared to this??

 

My 1969 L89 coupe with factory side pipes isn’t very loud at all. On the other hand my 1968 IMSA/TransAm Leldon Blackwell Racing race car is just perfect. It is nice and loud with its open side pipes.

Amelia Island Concours - 2015

 

They are much quieter , although vastly depends on the muffler. Stock '69 side exhaust is restrictive but very livable. I've had both Hooker side mounts w/ ST'S baffelsand now the OEM '69's.

 

I had the STS spirals in mine. Not too loud when cruising along, but woke up when you hit the gas.

 

I have both-

Mines a combo- straight pipe and/or muffler. Using electric cut-outs to go between straight unmuffled to full muffler-

I made my own 20" long glasspac type muffler- as from what I have read after 20" the noise reduction is minimal.

perfed SS metal- insinkerator (SS steel) garbage disposal rings hold it together-








I used stainless steel tie wraps- Summit Racing sells them

I wrapped it with exhaust tape- to keep the fiberglass from blowing out-


Here's the cut out design-





Used V-bands to clamp together- and can change out insert if I don't get enough noise reduction

 

Awesome work Richard.
literally threw the kitchen sink at her!

To OP......will be following as I will have this to deal with by Fall.

 

Have you ever heard the saying." If its to loud your to old!"

 

Hooker has three insert types for the Header/Side pipe combo, I've used two of them on my car, I had the small 21021HKR glass packs and they were quite restrictive at my HP level (480rwhp) but the sound level was reasonable for side pipes (the reverse flow style is listed for small block, the extra displacement and HP of the BB ain't gonna like the restriction). I'm now running the Hooker high flow and they are very loud. I don't think typical inserts will meet both requirements, it's a physics thing. The outlets are right by your ears and there isn't enough length to slow and cool the exhaust gas when you open the throttle up unless you restrict it.

Richards solution is as close as you can get I think, but lots of work.

I'd say you need to decide if the Side Pipe look is the most important or if you care more about performance and sound.

You can go with long tube Headers and electric cutouts (I have several buddies that have them) and get the best of both worlds (the side pipe headers cost you in mid range torque, the primaries are too long and the collector is too short). They were designed for road race rpm's and arguably weren't even the best at that.

I've also run them with out the big tubes at all, loud is very subjective. I can say that this configuration was in fact painful in about a half mile at 30mph in 4th gear and 4.11's.

 

suprspooky, I guess that is the big question... Do I need to go to under-car exhaust.
When weather is good my car is a daily driver. - I love it. except the noise.

I purchased the car (1968 BB) with 69 factory side pipes on it. Very restrictive....
I swapped to Dougs headers/sidepipes I was hoping I could get the sound down to a manageable level....
Maybe I am chasing windmills.....

I am hesitant buy inserts or spiral baffles as I do not want to keep throwing money at the noise issue...

Does anyone make a decent header for the 427 cars - decent meaning most of what I see out there (hooker, Headman...) simply does not fit well.
Dougs are great but they only make the side exhaust.

Does anyone do stainless for a 427?

 

Several folks on this forum have used both the Hooker and Hedmans with minor to no fitment issues. I am a ding the pipe if needed type (it doesn't hurt performance, as proved by Engine Master Dyno video) and I'm thinking about this solution my self (as well as the Richard solution).

I have a source here that made custom equal length for his 69 in stainless (his is a high 10 sec BB and I saw the Headers on car, on a lift, very nice), I think he told me $1800ish (I can find out for sure, if you want to explore).

 

I am in the same situation. Currently I have the STS spiral inserts in and it is loud. Like real loud when you get on it. So I just purchased a set of Doug's D952 which are the most free flowing inserts they make. I will install these and see how they compare - might be able to do that this weekend. If these are still too loud then I still have the Doug's medium (glasspack) D950 and I can try those. Definitely a trial and error thing though.

 

I believe the STS baffles originally came with a capped center tube that could be "uncapped" for better performance and louder sound but the more recently produced ones do not even have the cap. Do you have the capped version? I would cap them and run them first before spending any more money.

My Dad had a '69 Vert with an L-48 and Hooker side pipes. That amazing sound is impossible to create without side pipes. I always wanted to re-create that sound in another car. They were the Hooker Reverse Flow (quieter) inserts. Restrictive? definitely. Loud? maybe, but never painful.

 

https://www.jegs.com/p/Moroso/Moroso...44819/10002/-1

 

Nice! They list a 4" OD. Do you know if they will fit inside a standard 4" side pipe extension?