Thanks for the info man! Now I know I can make a 05/06 fit too, so hopefully Blue Dream will sell that one he has to me, and I can check it for the valve before I install it. That settles the question, and finally gets me the OE muffler I need. Plus puts some coin in Blue Dreams pockets for contribution

 

Wow this is very interesting.

* This whole time I thaught my muffler was messed up flowing from just one tip but now Im relieved. lol

 

if you guys just want to see inside the 05 muffler, I am in austin, I can cut it open and takes pics and post them if you want to save the shipping

 

Another update. It's been almost 2 weeks driving with the setup and the ECU has adjusted. The car is definitely behaving differently. Here are some of my observations:

1) Right off idle, the throttle does feel softer. I think there is a loss of power from idle to about 1500rpms or so. It's not huge, but I do notice a minor difference. With a 5AT, you do spend a little more time in this range.

2) From about 2300rpms, power ramps up harder than I remember. So much so that in 1st (everytime) and even sometimes 2nd, wheelspin occurs from a roll. This didn't occur prior. It's almost annoying. This is on completely dry surfaces. It has been in the upper 50s to mid 70s so that might have something to do with it. Launching with my all season 17s will be very interesting this winter. Right now I've got newer Z-rated 245/40R18s out back.

3) A brake-stall launch (about 2500rpms) feels awesome. Again, harder than I remember. Gone is initial 2500rpm bog/lurch as you come off the line when doing a launch with a 5AT (brake stall or not).

4) 5AT shifts aren't as refined at certain throttle applications. This is hard to explain and I noticed the same thing when I had my Borla TD. Prior to the mod, the part-throttle shifts felt crisp and direct. Now under semi-moderate throttle, it feels like 5AT is sometimes shifting fractionally too early on the 1-2 and sometimes the 2-3) and the power right after the shift, surges slightly. My guess is part-throttle engine vacuum is slightly different with the reduced backpressure. Since TCM shift mapping is somewhat based engine vacuum, I guess it's possible for the modded muffler to have an impact on shift timing under certain loads. Heavier throttle or very light throttle application shifts are normal.

5) When in manumatic mode (which I run all the time), will not downshift unless I put the throttle to the floor. Prior, if I was in MM 4th or 5th and I pushed the throttle 1/2 way, it would downshift. Not anymore. It's basically functioning like a 04.5+ 5AT now. Weird and I actually prefer it. More manual control, IMO.

6) More lower rpm engine braking. When letting off the throttle in gear, there is more of a pronounced engine braking effect. It's not huge, but it's still enough to know it feels different.

7) When in MM 4th at ~40mph and I push the gas 1/3 way down to pass, the surge in power (from the TC unlocking) is stronger than I ever remember.

8) Power feels stronger from 2500-5000rpms. Can't tell much of a difference above 5000rpms.

9) Gas mileage is unchanged.

10) Still sounds amazing.


Overall, the car definitely drives differently and seems quicker in most situations. It's hard for me to believe that a silly mod like this could create power and I don't quite see how it would be possible considering all that's been done is allowing more exhaust flow below 4500-5000rpms. Perhaps it's because the car is louder, it's fooling my senses.

 

Very interesting stuff! Thank you!

I've been too afraid to do anything with my exhaust setup since on my last car (I still own it, but is parked) after a muffler change drone was induced at 3-3800K rpms. I was thinking about just doing the Magnaflow to go with my OEM setup, but I believe that I will more to get that coupe like deep sound.

 

I'm VERY picky about how my car sounds and drives. I really don't like making compromises. With the 05/06 sedan midpipe, the drone was pretty aggressive under part-throttle under 3000rpms. Swapping back in 03/04 midpipe put the drone in control. There is still drone, but it doesn't overpower the cabin. It's basically like same level of drone my friend's stock 2011 Mustang GT 5.0 has. It's there, you can hear it, it sounds very sporty, but no one inside gets a headache, you can carry a quiet converstation, and hear music without having to turn it up. Yesterday I carted around a client for 200 miles who owns a stock 5AT 05 coupe and he was in love with the sound of the car.

The Magnaflow muffler will probably cause the same kind of drone. Whatever you decide, you should probably look into sourcing a 03/04 midpipe. It does a great at reducing drone while preserving decent volume.

 

^ Yes the magnaflow has some drone, after break in, its alright. I dont notice it any more.

 

so does anybody of any pics of the cutting of the muffler??

 

blue dream is sending me the muffler I've paid the shipping cost. I'll get to it as soon as I can once it arrives. I"m in Canada so I hope you guys are patient. I'll post as soon as I can.

 

I did this today and what a difference in sound!!!... I have Berk TP's so I was a little concerned on how it was going to sound, but to my surprise no rasp! And it does resemble a coupe a little more now... I have to admit, it is louder than before, but I think this will hold me off until I get an actual exhaust...

I have yet to actually let the ECU set itself for the change, but I'll report back and let you guys know of any changes...

My exhaust consists of: OEM headers, Berk Res. TP's, Coupe Mid-Pipe, and now modified '03 muffler...

Great mod for those that want a better sound from their OEM exhaust...

 

someone should do a diy for this

 

This is a DIY thread... The OP basically explained how to do it on page 2... That's how I did it... except I didn't use JB Weld, I actually welded the muffler shut...

 

I'm glad it worked out for you. I love the sound. I really need to make an in cabin video.

 

Yep sent last Friday, shipping to Canada was 6-10 business days. Thanks for doing this for us Matt and I hope the muffler arrives safely. I made a coocoon of bubble wrap and the lady at the PO was like WTF is that?

Had a friend with me and he was cracking up at her responses and facial expressions.

 

^ LMAO very nice, so I should expect that it'll be torn apart at customs for fear that it's a bomb?? LOL

Can't wait