Sort of a brief review ...

After I had a full 3" exhaust installed, my car sounded like crap and was basically not drivable--at least by my definitions of "crap" and "drivable". More than 10 minutes on the highway made your head pound. The car was loud under throttle, loud at idle, and loud just trying to cruise. The whole cabin resonated with obnoxious low frequency racket down the highway. I suppose if you're 18 and don't care about your hearing and all you have to do all day is sleep through classes, this might be okay. When you've got a job and care about your hearing and your sanity, loud exhaust down the highway ain't cool.

Since ZZP discontinued the Whisper resonator, this easily could have been a situation of tearing the exhaust off and sending it back to ZZP, and replacing with a smaller diameter exhaust with more restrictive mufflers. Obviously, this wasn't what I wanted to do, but options for a "streetable" 3" exhaust were looking slim. Not what I wanted to do.

In stepped the Dynomax VT. Summit delivered the muffler to my house in about a day after the order. For a month or so, it still comes with a $25 rebate, for an out-the-door price of $75.00. Summit kicked in a new customer bonus coupon good for another $20 on my next purchase. (Technically, I'm not a new customer, but 5-6 years apparently counts too). The muffler claims to be stainless, but out of the box, my impression is that while it might be stainless, it isn't T-304. It seems to be well-constructed, though, and basically a drop in replacement for most aftermarket universal mufflers.

The "gimmick" with the VT is a little flap in the muffler which pinches shut under low exhaust flow conditions. There's a little sealed chamber that houses a spring mechanism which holds the valve shut and, presumably, forces the exhaust to dwell in the muffler longer. Basically, you still have a huge sewer pipe exhaust when needed, but a tiny little exhaust when that's all you need. The rest of the muffler is basically a truncated UltraFlo which is a straight through perforated tube exhaust with Dynomax's loose pack fiberglass fill to absorb sound. Here's a cut-away from the company website: http://www.dynomax.com/images/mufflers/vt_lg.jpg

So, the big question, does it work on our cars, and what does it sound like? I haven't been able to drive for a long highway trip yet, but my impressions so far are favorable. There's a little pulse upon start-up before the valve closes, but then on idle, the car sounds stock. Or even quieter that stock. I'm not kidding here. You can actually take your car through a drive-thru and hear the speaker dude. There is nothing at all suspicious about the exhaust note--nothing screaming "give me a ticket officer because that was me rattling the concrete loose from the overpass."

Now, does that mean you can't rattle the concrete loose from the overpass? Absolutely not. Punch the throttle and the butterfly opens up and the car absolutely SCREAMS. And it isn't a Magnaflow "WHAAAAAAAA" scream either. It's more of a "BRRRRRRNNNNNTTT" metallic scream. Personally, I find this sounds much less "ricey" and more mini-midget dirt track car sounding. That's a stretch, but it's the best I've got. I've still got a Magnaflow 5" bullet acting as a resonator or sorts, so take that into account.

The weird part is everything in between WOT and idle. Highway drone appears to be mostly eliminated, but the verdict's still out until a long road trip. So far, though, I don't know how you would do better without putting on an RV muffler. If it isn't stock quiet, it's close. There is a little big of pulsating that can occur on light throttle application. It's hard to explain. Tim at ZZP described it as sort of a Subaru sound. That's pretty accurate. You might also call it sort of a Harley "thwacka thwacka" through a really huge muffler. I will be interested to see if it does this on the highway.

On deceleration the typical header burble and back popping is gone. I expected that, but I'll still miss it. Its probably a fair trade for a car that will cruise quietly. Once you take your foot off the gas, the car quiets right down with only a medium purr. Once it's back on idle, it's like shutting off the engine. Weird. It's almost too quiet. When's the last time you heard that from someone with a 3" exhaust and a header?

If you're thinking about picking one of these up, do not that there are two options: Either for engines up to 4.0L or for engine under 4.0L. The difference is the tension on the spring. I chose the muffler for engines over 4.0L since what really matters is the CFM being cranked out by the motor, and our engines under boost will really crank out a lot of CFM at high RPM--easily the equivalent of a 300bhp for a pullied motor. This ain't no normal 2.0L motor. The "under 4.0L" version would also be fine, just with a bit more noise around town and under light throttle on the highway.

Whichever version you choose, if you've been looking for a cure to a loud, droning exhaust, this is it.

 

I'm gonna play devil's advocate here, but anything that operates on a spring is going to fail sooner or later. The only question is when (especially a tiny spring like that which doesn't appear to be very secure). Not to mention that if the exhaust pressure has to push open the valve, it's going to create extra backpressure at WOT.

It's a really clever idea though. I'd love to see a shop do some dyno comparisons before I drop money on one.

http://www.dynomax.com/mufflers.php?muffler=vt

 

Interesting...

 

I had concerns about the backpressure too, but there's no extra backpressure at WOT. According to Dynomax, it flows 841 CFM at WOT. That's more than our exhaust ports are capable of flowing. I don't think it would take more than maybe, oh, 1/1000 of a horsepower to hold that valve open. You'll never see a difference on a dyno.

Regarding heat cycles, they have tested to 1 million per http://blogs.carcraft.com/6605791/ed...ign/index.html. More than enough.

The only problem was that some of the early units had a clanging issue with cammed motors without resonators due to a tight clearance and the uneven exhaust pulses. They did a slight revisions and took care of most of it. AFAIK, there are virtually zero LSJs with lumpy cams, so not an issue for us.

 

i might try this

 

wow that's one hell of a good idea, now all you idiots with 3" exhausts go get them asap so your car stops sounding like roasted *******

 

That's if it's wide open. The system has to build a certain amount of pressure before the valve will open, that's how valves work. This will rob you of performance. The question is how much.

 

Doubt you would lose even 1hp. Its not like its got a 10lbs spring or something lol.

 

could we get a vid? im kinda interested in this radical design haha

 

It would have to be fairly heavy otherwise it wouldn't do jack **** during normal driving.

 

I'm a huge fan of Dynomax. But I prefer the super turbo mufflers. They are quiet pretty much all the time, which is what I like.

 

I've got a Super Turbo on mine. I like it. It's basically OEM SS but a little louder. But still droney over time though. But 100% better than my worn GMPP mufflers and Ark N1.. Still flows very well also..

My exhaust consists of GMPP tubing ,stock SS resonator, and Dynomax Super-turbo muffler..

 

I'm also iffy on the spring thing in the VT muffler. I'm just going to stick with my Dynomax Super turbo.

 

I'll have to bookmark this to check on getting one of them

 

Yeah that's what i had on my old car they make any car sound good.
Have a magnaflow on mine right now, sounded good as **** till I added a header, now I'm kinda on the fence LOL.

 

U had both on ur old car???

 

Listen to the VT on the Evo on YouTube. Yuck. lol

 

ive looked into this, im not sold on it just yet

 

Yea, that car is cammed which Ryan mentioned was a problem. That's what I figure would happen eventually to all of them, just due to the wear on the spring.

 

Nah I had the dynomax super turbo on my old car.

On the RL I have a magnaflow, like I said though got loud as **** with the pacesetter in place of the stock header now .

 

The combination of cam and firing order seems to kill it on the Evos. Some of the early mufflers had a apparently had clearance problem, but those should be off the shelves by now for the most part. I have zero rattle issues. My thought is that if they can make a valve spring last, they should be able to make a spring on a muffler last. Tenneco (Dynomax) is a huge multi-billion dollar OEM, so I'm guess they did their homework on the longevity issues. There's a 90day unconditional warranty and a limited lifetime.

There's another video on Youtube of some guy with his 190HP Infinity G20. That gives you a better idea of the sound at cruise. Zero idea of the sound at WOT. It sounds mean, and stupid loud. A much nicer metallic edge than the smoother sound of a Magnaflow. Best guess is from 7dB to 10dB louder than a SuperTurbo based on some old magazine test results. That's about twice as loud. I would not recommend this thing without a resonator or bullet-type muffler upstream. WOT would just be deafening.

 

Well ive been interested in this muffler for my setup, and i will go ahead and take the plunge. Thanks for the review

 

Any one gotten one yet?

 

Interesting. My CTI 3" cat-back sounds like garbage.

 

even after the insert?