Anyone know whether the stock Evo8 or Evo9 muffler flows better than the other? I've given up on running an aftermarket muffler for street driving. My car is just loud with anything but a stock muffler due to cams, turbo, etc., and the law here in Virginia prohibits any non-stock exhaust that sounds "unusual" or "excessive."

The Evo8 and Evo9 mufflers have different designs internally. The Evo8 has a spring-loaded small round trap door to divert exhaust through the chambered portion and the Evo9 muffler has a perforated divider with holes in it that limits the amount of flow around the chambered section. Not sure why Mitsu changed the design or which is less restrictive under boost. Any of the OGs here have any idea or remember?

 

Since the 9 came with a bigger turbo and more HP from the factory I would assume the exhaust would be higher flowing. You can have a quiet exhaust made for you. The Road Race stealth exhaust is a local example of that and it does the job well.

 

I have the HKS Sport which looks almost identical to oem, it has a large oval muffler. With a 3" o2 housing, downpipe, test pipe its suprisingly quiet. Cruising you can barely hear it really. Add a small muffler like this: ultra quiet muffler to the test pipe or mid pipe section and I think it would give you what you're looking for while flowing better than oem.

 

Just dropped in to mention the Road Race Engineering Stealth exhaust like Biggie. Its what I run on my car and it is nice and quiet setup while still allowing me to make 580ashp/500awftlbs.

 

Plus one for the hks sport. It's not a true 3" piece but a really great sound.

no cat no resonator s2's
https://youtube.com/shorts/4thwYqhsgzc?feature=share

 

Here are the muffler differences between Evo8 and Evo9. Not sure if my Evo9 muffler was cut by a previous owner for a JDM bumper or if they are all short like that?

 

I really want to have full 3” flow when I’m at the track or autocross and noise isn’t a factor.. I have a cur-out before the muffler and, if I swap in my Works AB (which is kind of loud on the street, but a direct bolt-in replacement for the stock muffler), then I have a full muffled 3” system after some work in the garage. I’ve tried a number of catbacks but keep coming back to this setup. I’ve thought about the Varex, but it seems to be extremely restrictive when closed from what I’ve read and can develop rattles and valve sticking issues over time. The stock muffler isn’t great, but it’s way better flowing than a silencer or a tiny bypass hole in a valved muffler. I’m going to save that Evo9 muffler in case I switch rear bumpers some day.

 

They cut it. The Evo 8/9 mufflers were actually the correct length for JDM rear and too short for USDM rear really. IIRC the 9 muffler is slightly better sounding.

 

I am also from the NOVA area, I heard they recently made a revision in Fairfax County where they can't pull you over solely for loud exhaust alone. I think it had to do with the profiling of certain vehicles, etc. This also applied to dark tint and expired state inspection up to four months. Unfortunately since the speed limits are absolute, that makes all that go out the window since almost no one drives the speed limit. I rarely drive my car so I have been pretty lucky, running the AMS and it's pretty loud outside the car. Inside it's not bad at all. Nice to see another Evo owner actually using the car from track/autox.

 

Unfortunately, the law just changed back again: https://www.ffxnow.com/2022/06/30/un...arting-july-1/

It’s also broader and more restrictive now. Any change from OEM or equivalent from the engine block back is considered part of the exhaust, so the manifold, turbo, etc. all count.