As with the previous EVO chassis, we’ve suspected that the EVO X muffler exhibits qualities that may impede the quick and efficient flow of exhaust gas. WORKS recently cut open the OEM muffler to reveal what lies inside and here’s what we found.

The exhaust entry is fairly smooth with a nearly 90* bend upon entering the exhaust canister. At this point, some of the incoming gas can flow through perforated holes located on this internal bend (similar to what was found with the EVO IX) while the majority of the gas is allowed to continue on towards the left of the canister. (For now, we’ll follow the gas that sneaks through the small holes.)

The gas first enters a chamber on the right side of the muffler, but really has no other place to go except to another chamber even further to the right. To get there it must pass through a wall dotted with another set of holes. Upon entering the far right chamber, the exhaust gas works its way towards the rear and then through another internal pipe that leads to the central chamber of the muffler.

Returning to the entry point, the majority of the gas is allowed to flow through an internal pipe to a chamber on the left side of the muffler. It then must flow towards the back and center of the canister to meet a familiar foe. That’s correct: the spring-loaded flapper door from the EVO VIII muffler has made its return. In order for the exhaust to exit the muffler from the left side it has to build up enough pressure to force the door open. (Again, just like the VIII this takes some effort as there’s a fair amount of pre-load on the spring in order to keep the flapper sealed.) Once it manages to crack the door open, the exhaust gas enters the central chamber and meets up (head-on) with the gas flow from the right side of the canister.

From here, the two become one (briefly) and then go their separate ways (either left or right) exiting the central chamber via one of two internal resonators, which leads to the external outlet pipes/tips. (The pictures below are of the muffler with the top removed—one with arrows highlighting direction of travel outlined above, the other without.)

Not exactly the most direct route, but don’t worry. The EVO X StealthWORKS Performance Muffler has now been prototyped. We should have this on the dyno and I hope to grab a few video clips of both the original and modified versions. We’ll be sharing the comparison once available. Stay tuned!

 

Wow, that stocker definitely looks restrictive! Thanks for the cut view. I'm excited to see the results with the aftermarket prototype.

 

My God, what a mess. All they had to do was run the single pipe in two inches past the canister wall and make a left or right to either tip and eliminate the other tip. I'll assume all those bulkhead-type walls are for quieting the system and the extra tip is just for show. Like the 2003 and up Hyundai Tiburon. What a waste.

Thx for the pics. Also looking forward to seeing/hearing the prototype!

 

i can't wait to get the stock muffler off!

 

that stock muffler makes no sense from a performance aspect. seems like it would be a lot easier to just run two str8 pipes to the exhaust ports in the bumper...hell, one would actually be enough, and save on weight

 

That is WAY worse inside than I thought it would be.

 

But it does exactly what it's suppose to do, make the car as quiet as Mitsu deemed necessary.

 

I hate the silence of that car. I can't wait for ANYTHING aftermarket.

 

Just shows that the car is really screaming to be opened up.

 

man, this muffler will be sweet,

suggestion: can you guys also replace the flange and the pipe section that meets the muffler to 3 inches so that if someone decides to replace the rest of the exhaust, they can use this muffler as part of a true 3 inch exhaust system

Thanks

 

look at my sig


cheers
nebo

 

Well, the StealthWORKS muffler saw some dyno time over the weekend:



Overall, performance was good. We're looking at gains throughout the powerband with little change in sound levels. (I'll be the first to admit that I'm not as intimate with the sound of the X as I am with my VIII, though.)

Availability is somewhat limited at the moment, but we're in the process of acquiring a few more cores to limit any delays.

 

the way that stocker works make me sicks... ugh

 

What about it?

 

well, are you going to show pics of the new muffler or what? Cut out pics too please, so as to compare with the stock unit.