New Exhaust System

Old vs new. Sound is way better than what I had. It’s much snappier just blipping the throttle. Install was real easy except I had a factory bolt snap off which required me to cut the nut off the flange. I dunno if it’s factory to have the nuts welded to the flange but all of mine are. Thankfully the rest came out with ease and spd sends new bolts. Install took an hour including cutting the nut off by myself. I’ve got a couple of before and after videos I’ll edit and post in a couple of days. Nothing fancy but shows a good difference.

PSA, don’t do this when it’s a 100* outside.

 

Got 8 miles on it so far. It’s definitely a verbose system. May be because the previous owner removed the rear cats. Below 2k rpm’s it’s loud inside. Probably going to start driving in s5. Above 2k you can hear the rumble but not drone. Wife said it sounds great so I’m happy.

 

Badass! Glad you like it. Still awesome to me everyone noticing the same thing at first start of snappiness.

 

After another 40 miles, I’m contemplating throwing a couple of small high flow cats in place of the removed rear ones to try and tone it down in the lower rpm’s some.

Is it a packed muffler that is going to break in? I can’t remember.

 

Anyone have these installed with an SC? Id like to hear. Not that ill order but an idea if I want to move up to a 3" pipe

 

You know Rey is SC'd and most his videos and comments are from his super charged perspective.

 

lol did you read the first post?

 

It will break-in a bit yes. You could add the same cats as the fronts to the rear to quiet it down it or run the cat back and not the down pipes etc

 

So I understand flow and expansion of gases and why Toyota uses small piping and the little pipe inside of the large one to keep flow going but why? What makes this engine different than other v8’s? No other manufacturer I’m aware of uses the pipe inside a pipe and most use 2.75” piping instead of 2.5”.

 

I’m still on factory down pipes. The previous owner cut the two rear cats out.

 

Believe it's for scavenging and maintaining velocity on the vvti system. I know it was explained awhile back by another vendor.

Edit: Toyota hides a section of tubing in your exhaust system that is only 2" in diameter to keep up velocity, not backpressure, so that reversion is avoided and scavenging can occur. Retains low end torque too.

 

Yeah but theyre not the greatest lol

 

I understand that but why is it needed for this engine. Does the cam events not allow for great scavenging and keeping flow up? My experience is chevys, fords, and dodges and they don’t utilize those pipes to my knowledge. And run bigger pipes in general and don’t have issues upgrading exhaust pipe size assuming you don’t go crazy.

 

Happy to text more videos if needed

 

This post from tundratalk was from 2013 when Keith was working on the dual exhaust.

I have recently visited the exhaust masterminds at JBA. Their 'new products' engineer Don Linfors and I had an in depth chat about Tundra exhaust systems (my favorite subject), I explained to him that I installed 2.5" diameter mid pipes on my stock exhaust manifolds. I then complained that there was a major loss of low end torque. The grunt of my beloved truck was now gone. It pulled much harder at the top end (7HP and 15lbs tq harder to be exact:lol5: on the dyno)
But on the freeway and around town it sucked. It was hunting for gears, I had to step on the throttle much harder than usual to get the truck to move forward, etc. I then told him I took out the hidden pipe and showed him the above pics. He said matter of factly, that's because you slowed down your velocity and it caused reversion.

Before I 'googled' the term reversion I asked him for a laymans definition. His definition was much too detailed to say it was laymans, but simply put, once again, it's the opposite of scavenging. Without that tiny 2" hidden pipe the exhaust gases won't go fast enough at moderate engine speeds to create scavenging. The exhaust gases aren't going any specific direction. They're under pressure and that pressure just goes to the path of least resistance. Instead of siphoning out to the tailpipe, they actually back up. The high pressure pulse of the first firing cylinder actually backs up into the next cylinder in the firing order and during valve overlap instead of pulling out the exhaust gases and pulling in the intake charge, that pressure actually pushes the intake charge out of the cylinder and back into the intake manifold. This causes less a/f charge to be burnt as now there is only as much a/f entering the cylinder as the piston can pull in, no more. You see, scavenging during valve overlap will actually supercharge your engine and make in take in more than 5.7L displacement, but reversion stops this supercharging effect and performance suffers during normal driving.


So let's sum it up, Toyota hides a section of tubing in your exhaust system that is only 2" in diameter to keep up velocity, not backpressure, so that reversion is avoided and scavenging can occur. This 'supercharges' your engine making more power. Back pressure is an after effect that unfortunately can't be helped unless we make the exhaust tubing diameter variable.

 

I’ve seen that and understand it but it doesn’t explain why this engine is so sensitive to this while plenty of others aren’t.

Example, on a 5.3 Chevy, I know I can upgrade to a 3” exhaust and gain power and lose nothing. Why on a 5.7 tundra does doing the same have a different affect?

 

I don't know exactly but read about the vvti exhaust lobe overlap creates some oddity. But that's the extent of what I read or saw.

 

Installed mines today I love it... gonna be selling my dirty deeds trd replacement with tail pipes in next couple of days....

 

Got close to 200 miles on mine now. I’m definitely going to be adding in some high flow cats in place of the missing oem rear cats to try and cut some of the noise out below 2000rpms. It sounds great though and I’ve got no complaints. Guess I’m just getting older.

 

2nd tank of gas. 12.6mpg.

It's the little things .

 

What about inline resonators? I've heard good things about Vibrants, unsure if there's enough room.

 

Not enough room. If it had full tail pipes then yes. I’d rather the cats anyways. I’m not a greenie by any stretch but for taming exhausts, cats work great. Ruined to many exhausts in my youth deleting cats in search of power. So little gained at the expense of rasp and noise.

 

Does anyone know if you asked for the wideband bung in downpipes if they are on both sides? I can't see thanks to my cat defender plates.

 

I believe someone mentioned a few pages back that they had bungs on both down pipes.

 

I asked for mine to be on the drivers side and they put one on both.

 

Wish I had asked for both.

 

I have seen Innovate's bung is too tall, should I use this smaller one I have?

 

I’d say it depends on the size of your bung hole. But that would be TMI.

 

You’ll want the shorter bung to allow the sensor to be in the exhaust tract further.

 

My buddy's 2017 had them welded on.