Looking for a unicorn muffler.

[downl50]

Bovey, any progress on making your selection?

I'm down to Borla XS pro, Dynomax Hemi Turbo, Magnaflow (either 12289 or the wide/shorter model), Spintech 3000XL plus. These seem to have all gotten votes of lower pitched with no drone. I don't know about overall db level though.

I came across old post from Chevelles.com -- not sure what to make of the supporting 1500hp claim but some interesting tips that I'm planning to try including the Car Chemistry inserts and doing 3" to the mufflers then 2.5" to tips. I have 1 7/8 primaries with 3.5" collector made by Lemons.


"(1966 Chevelle)
Starting at headers:
Car Chemistry 3-disc collector inserts

(Ultraflow #24215 2.5 12" Bullet) <---No room on Camaro



Dr Gas X-Pipe 2.5 in/out

Ultraflow #17236 2.5 Mufflers 24" case

2.25 Tailpipes

Quiet is an understatement. Pure cam & header "ping" inside.

Full-throttle is more like an RPM-based ever-deepening
"tuned" sound, somewhere between a NASCAR & an F1 exhaust.

This particular combination is the final culmination of 30-plus
years of experimentation & a lifelong interest in IC gas flow &
exhaust systems. This system could support a 1500 hp/2000
cfm engine w/o any appreciable difference vs. an open exhaust.

It represents TR's maxim "Walk softly and carry a big stick" well.

There is probably more mythology & misunderstanding
regarding exhaust system design & performance than
any other choices to be made in the car's build. What
works versus what doesn't falls way behind what anyone
thinks "sounds best" on most exhaust system decisions.

HTH someone!!"

[bovey]

Bovey, any progress on making your selection?

Yes, sorry for the delay. I've had a hard week. Before we discuss my findings, but we need to address this 1500 HP Chevelle below.

I came across old post from Chevelles.com -- not sure what to make of the supporting 1500hp claim but some interesting tips that I'm planning to try including the Car Chemistry inserts and doing 3" to the mufflers then 2.5" to tips. I have 1 7/8 primaries with 3.5" collector made by Lemons.


"(1966 Chevelle)
Starting at headers:
Car Chemistry 3-disc collector inserts

(Ultraflow #24215 2.5 12" Bullet) <---No room on Camaro

Dr Gas X-Pipe 2.5 in/out

Ultraflow #17236 2.5 Mufflers 24" case

2.25 Tailpipes

Quiet is an understatement. Pure cam & header "ping" inside.

Full-throttle is more like an RPM-based ever-deepening
"tuned" sound, somewhere between a NASCAR & an F1 exhaust.

This particular combination is the final culmination of 30-plus
years of experimentation & a lifelong interest in IC gas flow &
exhaust systems. This system could support a 1500 hp/2000
cfm engine w/o any appreciable difference vs. an open exhaust.

It represents TR's maxim "Walk softly and carry a big stick" well.

So this Chevelle guy claims he put 1500 hp through 2.25" tailpipes? I need a dyno video. Or is it a 3000 hp system chocked down to 1500 hp due to the exhaust? ;)

In all seriousness, I did have Burns Stainless run numbers on my engine. I gave them exact details, including how I plan to use the truck and what part of the power band I wanted to control with the exhaust. Burns came back with a header design and a reco on running dual 3" or 3.5", but based on the rpm levels I'll operate at they suggested the 3.5" is the way to go. It also gives me room to make more power and be able to use the same exhaust.

Another thing Burns said: "For a successful exhaust design it should always get bigger as you build from the head to the tailpipe". The Chevelle guy does the complete opposite. Burns is not just anyone, they design headers for the Pratt and Millers Corvette Race Teams. I'm willing to believe there are different ways to do things, but if I was building a 1500HP car, I'd need more proof than a forum post for that set-up. Thanks for sharing this, such a curious claim!

Thank you to everyone with their responses. Appreciated very much.

I'll be back with my research. Sleep. Now. Long week.

[HandOverFist]

Yes, sorry for the delay. I've had a hard week. Before we discuss my findings, but we need to address this 1500 HP Chevelle below.





So this Chevelle guy claims he put 1500 hp through 2.25" tailpipes? I need a dyno video. Or is it a 3000 hp system chocked down to 1500 hp due to the exhaust? ;)

In all seriousness, I did have Burns Stainless run numbers on my engine. I gave them exact details, including how I plan to use the truck and what part of the power band I wanted to control with the exhaust. Burns came back with a header design and a reco on running dual 3" or 3.5", but based on the rpm levels I'll operate at they suggested the 3.5" is the way to go. It also gives me room to make more power and be able to use the same exhaust.

Another thing Burns said: "For a successful exhaust design it should always get bigger as you build from the head to the tailpipe". The Chevelle guy does the complete opposite. Burns is not just anyone, they design headers for the Pratt and Millers Corvette Race Teams. I'm willing to believe there are different ways to do things, but if I was building a 1500HP car, I'd need more proof than a forum post for that set-up. Thanks for sharing this, such a curious claim!

Thank you to everyone with their responses. Appreciated very much.

I'll be back with my research. Sleep. Now. Long week.

The way I read it is he states it "could" support that level...not what it currently is.

[bovey]

The way I read it is he states it "could" support that level...not what it currently is.

"could" excellent point.

[downl50]

Agree, I don't really know what "supports 1500hp" means. My read from a few dyno tests done by magazines is that anything north of 500hp is at least somewhat restricted by a 2.5" system. I have had several manufacturers suggest doing 3" to the muffler and 2.5" tips.

I'm going to do this with the Pypes kit with tips out the back and run the largest magnaflow I can fit -- need to measure but several people claim they've fit the 5x8x24". I'm going to try to hold off on a second set of mufflers but now seen several people adding a small round muffler to reduce volume.

[TXsilverado]

don't read too deep into internet racers/gurus. pay attention to the guys running fastest and setting records. NONE of those guys are running 2.5" exhaust. period.

if your car is N/A, dual 3" will more than likely take care of your needs

big nitrous (not a dinky 200 shot) or higher boost level blower cars can start looking at larger than 3" duals. and of course, it all depends on what you're wanting to do with the car.

[CSG]

FWIW I have made 680rw on a mustang dyno with dual 2.75" factory GT500 mufflers. They were not overly quiet but not terrible. This was a forced induction car though.

[CarlC]

Here's some interesting info https://www.youtube.com/watch?v=_PVXvHkr-Vs&t=762s

It compares 2.5" vs. 3" in an engine with likely a very similar airflow requirement.

I just finished putting a full 3" exhaust with a Magnaflow X-over and dual 18" long Magnaflow mufflers in the Camaro. It's 10lbs of stuff in a 10lb hole, but is surprisingly quiet. It does, however, make all the right noises at WOT.

[CSG]

That video shows Magnaflow mufflers. I am pretty sure that atleast at one time that series was not 3" on the inside.
I picked up 50rw on a turbo car by going up to 3" from 2.75" but I also changed the type of muffler. This was an 900 hp or so car. Turbo cars are certainly different though so I don't know if it even relates...

[bovey]

I've spoken to Burns Stainless and recently Vibrant Performance stopped in the see my build after seeing it on Facebook. Both of these companies say versions of the same thing. There are a large number of variables when building exhaust. NA vs. forced? Use of engine, road race vs. drag vs. etc? Where you want to help the engine make power? Pure street car vs. dual purpose car vs. track only? Space and and the actual space you have can dictate your options too. You really need to weigh the options based on your build and use needs.

Headers for example, depending on the use, have room to be flexible with their design. If you are a pro team looking for squeeze every ounce of power of of an engine - then NO, you need to get really harsh on the build specs. Forced induction guys just make it fit and they can because ram a crap load of air into the engine, NA cars need a little more care, but again, unless you are going all out pro level - you have wiggle room.

Also, too CarlC's point, I'm after regular driving noise, just to cut down on fatigue - WOT is WOT.


All of this being said, here is what I found out. I have called and spoken to the tech lines of Borla, Spintech, and Magnaflow. Everyone was nice and took the time to talk.

1) Borla recommends using their XR1 - 40946

3.5"/3.5" out - 4.25" x 8" x 16" case size - stainless steel. I've listened to a few on youtube and like them, that being said the videos I found did not have the engine mods I do.


2)Spintech. I can't recall the guys name, but I have the feeling he owned the place. Very nice, super willing to talk. He wants me to run 3", so much so he would not give me part numbers for 3.5", he said I did not need 3.5". Even after I explained to him that I had an company work out the flow rates for my engine, he seemed convinced 3" was sufficient and their street cars all use 3". Again, I explained my truck is going to see some fairly harsh competition use and prolonged rpms, he stuck to his 3" street car POV.

He recommended these two mufflers:

A) Superstock 1000XP - 4" x 9.5" x 14-15" case size


B) XR90 - centre in/side exit (think AAR Cuda) 4" x 10.5" x 18"-20" case size


For stainless, Spintech requires a 2 week build lead time. They are built to order.

3) Maganaflow recommends their 12909


3.5"in/3.5" out - 5" x 11" x 22" case size. Magnaflow uses packing to aid noise reduction, unlike the others. So their sound will change over time. Again, I like the sound of these.

In general terms the bigger the case, the more sound they control. This gives the Spinach XR90 and MF the edge. Based on the videos, and a discussion with my guys at my local speed shop (Performance Improvements), I'm leaning towards Borla. I'd kinda like the try them all. As for cost, they are all in the same-ish ballpark.

The headers are done, I'm just looking into heat coatings as I've pushed the engine back about 18" and the headers are beside the footwell now. We've just torn the truck back down again to paint the firewall and properly assemble the 427/OS Giken clutch/Tranzilla t56 and stuff it back in. Looking forward to firing this stuff up.



I'll come back with an update when things happen.

[CSG]

I had spintech on my road race car and they were the loudest muffler I have ever owned (size for size)

[downl50]

I ended up with 2.5" all the way out the back with magnaflow oval 18" (largest I could fit). Great sound quality, little louder than my ideal so may try to add a second set or maybe even cats. This is with a 580hp 427.

[cdrod]

... I put the largest Magnaflows I could fit behind my big block Olds in my 442 that are 5x11x22. ...

You got a 22" long muffler to fit under a 442? Was that an A-body or a G-body? Were you running tailpipe or dumping in front of the axle? Did the exhaust hang down lower than a stock system? I'm building a '72 442 convertible and I don't want it to be too loud. I'm leaning toward a Dynomax Super Turbo #17749 but it's 20" long, the stock muffler was only 17" long. I want the exhaust system to tuck up nicely under the car; don't want it hanging down where you can see it. Thanks for sharing your experience.
Rodney

[rennat_2006]

Hooker maxflow or maximum flow mufflers. You can tell it isnt stock at idle, good sound while accelerating normally, no drone and quiet cruise, and gets loud when you step into throttle real hard.

They come in 3.5" sizes.

There is a sound level(db ) and horsepower/tq test of like 15 different mufflers all on the same car all dyno'ed and db'ed floating around on the internet somewhere, i will try to find it and post a link. These max flow mufflers were in like the top 3 in both hp and sound levels with #1 being the most quiet.

They are my go to muffler now for just about anything, drone drives me absolutely crazy and constantly having to yell to talk to the passenger next to ya is no fun either.

[USAZR1]

You got a 22" long muffler to fit under a 442? Was that an A-body or a G-body? Were you running tailpipe or dumping in front of the axle? Did the exhaust hang down lower than a stock system? I'm building a '72 442 convertible and I don't want it to be too loud. I'm leaning toward a Dynomax Super Turbo #17749 but it's 20" long, the stock muffler was only 17" long. I want the exhaust system to tuck up nicely under the car; don't want it hanging down where you can see it. Thanks for sharing your experience.
Rodney

I'm going to install a pair of those 20" Dynamax mufflers on my 70 Elco. It's running a 383" sbc that probably makes 450hp. The #17749's are quiet and have virtually no resonance.
I've got room for the 22" Dynomax Turbo mufflers but the price is quite a bit more.

[Jeff70]

Several of Mark Stielow's cars are running the Borla XR1 with 800+ Hp. I've heard most of them in person and must say very mild at idle and under normal driving conditions until WOT then it sounds like WAR.