Once the intake tube and cone filter adapter (CAI) in my other thread are done (prob this week or next weekend), I'm going to begin working on an exhaust. It seems like all the shops are running 3" tubing. I'll probably run 3.25" or 3.5" tubing.

I'm getting old(er) and don't really care for ultra loud exhaust systems anymore. I'm looking for input on an off the shelf muffler which is very free flowing and still quiet. I can build a muffler from perforated tubing, stainless wire mesh, and ceramic insulation sheeting, but it's a whole lot of work.

In the past I have run Walker Dynomax Super Hemi Turbo mufflers, because they are very quiet and very free flowing. However, I have only ever found them in 2.5" diameters, and the muffler is physically huge. I could run two in parallel, but then the mufflers would be twice as huge and I don't really want to deal with that.

Has anyone seen a published Sound Pressure Level test on a variety or import style mufflers? Is there a link?

 

This seems like a "best of both worlds" solution to your needs.

http://xforce.com.au.tmp.anchor.net.au/cars/view_car/29

 

Why is it you want to run 3.25 or 3.5" tubing?

In my own 'personal opinion'... I think 3.25 or 3.5 is to big for a stockish setup
(500whp and below).

3" is good enough for 650-750whp if i'm not mistaken.
3" (parts, tubing, resonators, and mufflers) are also more commonly on the shelf items, so it would be easier to source.

I will not knock you for doing it, in fact I would incourage you, just to see how a 3.25 or 3.5" exhaust would react on a X vs a straight 3" setup.

I've tried magnaflow mufflers and with a resonator or two... you don't notice you even have an exhaust.. On a full street set up w/ 2 resonators and a hi-flow cat sound levels are under 89dbs at idle up to about 4k rpms.

Just my .02 cents, Good luck!

-Chris

 

magnaflow ftw magnaflows for the most part don't sound ricey

 

You've got to work on thinking in Evo instead of thinking in Mustang.

On a serious note, no shops make a system that big for an X that I am aware of. You'd be best off looking into a complete custom job if you really wanted to do it. IMO, nobody here is going to know of a good 3.5" I.D. muffler. Even then, there won't be any gains using a muffler or piping that big, only possibile clearance issues.

There have been a couple of low 10 second Evos (VIIIs and IXs) run through the shop with a built stroker motor and either a 35R or a 37R running a full 3" system.

If you want something quiet under normal driving, look into a cut out or even a dump tube for the least restricted flow. Good luck.

 

just use 2 resonator mufflers before the last muffler. wont hurt flow that bad and will sound quite as a DD and still nasty at redline!

 

650 whp sounds like an awful lot for a 3" system. I guess it depends on the backpressure through the system though. My "Mustang" (still thinking in Mustang terms) put down 880 rwhp through a 3.5" system and the backpressure was pretty high. I vaguely remember it was around 3 psi through a full length exhaust pipe with no muffler. That was 2003 though, and I don't remember the details very well anymore.

I was figuring I would try a larger tubing to see if it works any better, but without a 3" system to compare it to, who knows. Also, I can't see that it will hurt either, so why not? I planned on building the whole system myself, and I estimate the tubing will run about $220-$250. If I have to run vbands the total will be higher, but I don't know if I will have to. I suspect tubing of that diameter will not work with the factory flanges.

I made a bung adapter a couple weeks ago in order to test backpressure through the factory system. It's basically an old O2 sensor which I cut apart, and welded in an NPT adapter. In that NPT adapter I installed a bronze NPT to 1/4" flare fitting. From here I can run a 1/4" copper tube to a pressure gauge and see measure the backpressure through the system, behind the wideband bung I installed in the downpipe. It's simple and ugly but it works fine, and I've used similar items in the past.

I'm also curious to hear the difference between "thinking in Evo" and "thinking in Mustang". I thought in Mustang from 1989 through 2004, and it's hard to break old habits.

 

Very curious to see what the backpressure is on a stock Evo X. Even greater if you upgrade exhaust in the future and run another test and compare the results.
Thanks for your effort.