Exhaust system dyno results?

Ok fellas, I’ve got some thoughts…

1) There are a few exhaust systems that I’m eyeballing. Without naming names, one is the self-proclaimed gold standard for Tundra exhausts and the other two are relatively newcomers. None appear to be bad options.

2) I have zero interest in the big name exhausts that you may find at Summit or the like.

3) Shiny finish means little to me, as it’s under the truck. I barely wash the topside, let alone under the thing. BBQ paint vs shiny stainless finish means nothing to me. Performance and durability trump.

4) Every manufacturer claims theirs is the best.

5) Most consumers claim that their purchase was the best.

6) A lot of that above is subjective.

7) Has anyone done real dyno testing on their truck with a before and after with a specific exhaust system? Claimed gains mean nothing without data…

8) Yes, sound matters. So does performance. Since sound is 100% subjective, performance gains are all I really care about at this point.


I’ve touched on this before, but got no response from any manufacturers. If they’re willing to provide verifiable data that backs up claims, I will gladly put my money down.

The three systems I’m most interested in are BAMuffler, SPD, and TWC. One definitely has experience on his side, but experience only goes so far. Not saying this is the case by any means, but it can lead to complacency. Are the newcomers actually tipping the scales, or are they simply more shine?


Again, not trying to ruffle feathers! A new exhaust system isn’t cheap. I don’t think it’s too much to ask if I’d like some proof before I buy!

 

Draggy time improvements and boost loss over my previous system. And plenty of dyno numbers from spd on other rigs as they work directly with tuners and shops for improving their items. They just did a Raptor R and saw good gains.

 

Thanks for this, Rey. I forgot that you’d mentioned some of this before!

 

A bit of a tangent, but I'd really love to see Dyno of SPD's new downpipes vs LTH's. This may end up taking some planning to "just do it"

 

Try MPI Exhaust Technologies. I'm running their system on a 2011 Crewmax.
No affiliation with them.

 

We can go for a ride if you want lol

 

Oh, God. I just threw $21K into a new well and about $9K on a Baja fishing trip with my son for next month. Not sure I can afford a ride with you for a bit! Lol.

But, yes. That sounds like a good time. I did drive close by your neck of the woods last Thursday when I had to run to Warrenton for the day.


Curious how the SPD noise level is in the cab when towing a travel trailer…

 

I’d like to see a comparison between a full system with downpipes and their basic cats vs just the cat-back on a N/A truck…

 

I’d start with the catback first. The down pipe section is on the louder side.

 

Word.
Any appreciable performance difference for the N/A group with the downpipes, that you’re aware of? I know, I’m boring…

 

Absolutely should see gains since the down pipes remove the secondary cats and add In high flow primaries

 

I built said system, by hand, from scratch, one and a half decades ago. And Dyno; street, track tested it. I can tell you what will happen with stock manifolds and no cats.

the Dyno numbers will wow you. But when you take it on the street and your truck barely ever goes into 6th gear due to low end torque loss you’ll be sorry you did it.

I still have the fixtures to build non catted mid pipes for stock manifolds. If they worked, I would be advertising them.

 

Thanks for the input, Keith. I’m not thinking about a system with no cats. Potentially one with less cats, which are different than OEM.

 

Anyone with SPD downpipes and cats have trouble with 6th gear holding on the freeway? With my tuning, I hold 6th well, although it does downshift on steeper humps and such if using cruise. I need to modify that tune a bit.

 

One more thought I had on this, Keith. And, I’m just spitballing here because I’m not an exhaust guy.
When you built this catless system that killed low end torque, was it with the rest of your normal system behind it? Nothing wrong with your system, just wondering if the torque loss from removing the cats is potentially offset with the dual 3” pipes that are equal length and utilize an X-pipe.

Not trying to be a smartass. Just seeing if things are truly being compared apples to apples.

 

I run spd cat back with some flow master high flow cats in the secondary cat position and stock manifolds with factory main cats. Zero issues holding 6th at either 50 or 80. Mileage hasn’t changed around town or on highway either. Almost tempted to load the factory tune to see if that makes a difference but I doubt it.

 

Unbolt your stock R2D2 sized muffler and take a look at it, the pipes are tiny and the muffler is restrictive. Anything that replaces that section will give performance gains. 1000$ budget goes to a 8” BAM system, if you have a big budget then it’s the full BAM 3” race exhaust with ARH LTH. I believe there are BAM dyno sheets for both of these.

 

Order placed. Hoping to see it on Monday or Tuesday, and install Tuesday night. Will report back with mileage and output impressions.

 

Ok. Two trips in with my new SPD cat-back system. Quick backstory; I drive the same 18.9 mile section of rural highway from my house to the office every day for the 6.5 years I’ve owned my truck. After 167,000 miles, I’m pretty well in tune with how it performs.

There are a couple small rolling hills that I hit every time I drive. I drive the exact same speed with cruise control every day. I’m familiar with the exact point where my torque converter unlocks on these hills when using cruise.

New exhaust, zero unlocking of the torque converter. This can mean only one thing, from what I can gather. The truck requires less throttle input to maintain the level of power necessary to maintain the speed.

I believe that there is no loss of low end (approx 1,850 rpm) torque with the SPD cat-back system on our N/A trucks. I said it in another thread, but will repeat it here since it is directly related to my original post. I have no dyno results, but I’m pretty sure we’re over the hurdle that says you lose power with 3” exhaust. If I’d lost power, it wouldn’t be holding 6th gear with the TCC locked.

Sound… I can’t speak on if the system sounds “good”. That is too subjective. I do like the rumble at startup. It is definitely louder through the rpm range, but doesn’t get overly raspy or nasty loud. I’m not detecting any drone, just a bit more sound level at cruise. I’ll need to tow my trailer to see how that sounds. My guess is it’ll be a little louder than I really want, but we’ll have to wait and see before I confirm.

 

Bringing this thread back to the top for an update. It’s been right at 2 months and 5,000 miles since installing the SPD cat-back system.

Nothing real negative to report, but it is (in my opinion) louder than I like for a daily driver. The tone is beautiful, but the volume makes it difficult to use Bluetooth for phone calls. I drive a fair amount, as you can see by my 172,000 miles on a 2018 truck, and need to be able to take calls on the road.

So, I’m gonna be the guinea pig here. There’s been a lot of previous discussion about pipe sizing and performance gains, as well as sound. I’ve just ordered a 10” BAM system from @dirtydeeds to see how it compares to my current system. I do have stock exhaust manifolds, cats, and downpipes.

I’ve not considered the low rpm noise to be drone with the SPD, but I’m very curious to see what changes with my experiment. So, I’m gonna put on the DD 10” system with no Hemholtz resonator to see how it sounds. Assuming it will be irritating…. Then, I’ll add the resonator and see how much it changes.

In the end, I’ll let you all know what I find to be different and sell off whichever is not the best system FOR ME.

Stand by!

 

@Chad D. did you leave the SPD system dumped under the bed after the axle? In previous vehicles, that has always made a big difference to me in cabin noise; moving that noise to an exit outside of the vehicle space - ie. a tailpipe - has always dropped the noise level significantly.

That said, your experience mimics what I’ve heard about the SPD system. Sounds great, if a little rowdy. Interested to see where this goes.

Have you considered a straight through resonator such as one from the likes of Vibrant Performance? Their Ultra quiet resonator looks promising and for $130 wouldn’t break the bank. Of course, if you used it on the SPD system you would need two. Or you could try a y pipe after the dump and stitch in the resonator just before then end of the tailpipe. My sequoia from the factory has a resonator about 8” from the end of the tailpipe, for example. I’m considering SPD down pipes and adding a Vibrant resonator to my system to try and realize better flow of the down pipes while keeping the existing sound level - or even a tad less when on power, like towing on the highway.

Helmoltz type resonators work really well at targeting specific frequencies, which is why they work so well to combat drone. They don’t do anything for overall sound levels (except at those specific frequencies).

 

I'm still waiting for a high flow great sounding mufflers that don't drone at around 2400rpm that don't use valve flaps.

 

I built a set of tips for my spd and below 2k it droned bad. Above that it was very quiet. Took them off and will be leaving them off. The sound below 2k with no tips is just the exhaust rumble and not actually drone like I thought and I’m ok with that.

 

Like the thread title suggests, are you going to dyno both systems? For science.

 

No if I’m footing the bill.

If someone has access to one in The Willamette Valley, I’m absolutely game. Would need a pull or two before the SPD comes off, then another after the DD goes on. With inconsistency between machines, it would need to be on the same dyno both days. Luckily, our weather will be easy to count on for the next few months.

Unfortunately, I don’t have easy access to a dyno in my contact network. Find me me for me between Salem and Roseburg!!!

 

Spd knows of one I’m sure. They work with tuners on their systems all time and dyno info.

 

I'm actually working a connection for a Dyno in Eugene. Private shop friend of a friend thing...

 

Think they’d be down for some unbiased fact finding? I feel like we would need graphed results that can be overlaid to highlight any differences. If I can get the graph files in PDF, I can overlay.

 

You have my attention…. I’ve already been on a dyno for my tuning, so not expecting to see if there is much left on the table with my setup. This would just be an apples to apples comparison between two exhaust systems. Would need to show across the board results, as PEAK HP and torque gains don’t tell the whole story.

 

Not really worth noting, I do have my dyno results from tuning with before and after numbers. But, this won’t mean shit because all dyno’s are not equal.