I've had a Flowmaster muffler on my 240 for about 12 years. I bought an MSA 6-into-1 header, their 2.5" stainless kit (with DynoMax muffler) and had it installed by a local shop. I didn't like the DynoMax muffler too much, and it was occasionally rattling, and after a few tries at the original shop to fix it,  I took it to another shop. I had them put on a Flowmaster, and they did a few very minor tweaks to the piping so stop the bumping and rattling. I liked the sound better, and it served me well for awhile.

 

About a month ago, due to ignition issue I was having (long story, suffice it to say don't use a MSD Blaster II coil with a Pertronix Ignitor) I had a very loud boom of a backfire one day and the Flowmaster was damaged a little. Somewhere inside of it, some baffles or chambering or whatever got blown out of bent, resulting in a bit more of a "hollow" tone. I didn't have any visible damage that I could see without putting it on a lift, but after a few days I started to think it was leaking a little.

 

I've always wanted a "twice pipes" setup, but that wasn't in the cards for now, so I tried finding a single-inlet, dual-outlet muffler that would fit the bill in terms of outlet size, orientation, and overall muffler length. No dice.

 

I started looking into MagnaFlow mufflers, and sure enough they have a normal oval muffler in the center-inlet, offset-outlet configuration I needed. I read on this forum and others that MagnaFlows are a little more quiet than Flowmasters (but flow better) so I wasn't sold on a direct 9"x12" oval replacement. I did a little more research and found a 6" round muffler with offset inlet and offset outlet that I thought would work. I figured it was a little larger than the 4" or 5" round ones that people say are too loud or drone without a resonator. Plus, the muffler shop guy thought the offset/offset configuration might work pretty well without major bending/finessing, so I ordered one from Summit (part # MPE-12636).

 

Sure enough, it was a great fit. Only took a half hour to swap the mufflers, fit the new slash/cut tip, and weld everything up. I love the sound. It's quieter at idle, and maybe quieter in the car overall, but it's louder outside the car to the rear as the RPMs rise. It definitely sounds more like a sports car now. I compiled a before-and-after video and put it on YouTube (see below). It sounds different under load that when just revving, but you'll get the idea. Under load, it starts off sounding sounding like an "angry trombone", and then moves into "angry trumpet" territory at mid-to-high RPMs.

 

http://youtu.be/jXrf_ORXThY 

Sounds good.

Ok, it sounds sporty, but instead  of using the tailpipe for the video, how about something nicer like a girl?  A tree maybe?   There is probably a better way to record the exhaust sound than video-ing the tailpipe, like a microphone taped to the tail...  I will try it if the weather cooperates;  I have a quality digital audio recorder with a remote microphone.

I'd be interested in hearing what the issue was with the MSD and Pertronix

Ok, it sounds sporty, but instead  of using the tailpipe for the video, how about something nicer like a girl?  A tree maybe?   There is probably a better way to record the exhaust sound than video-ing the tailpipe, like a microphone taped to the tail...  I will try it if the weather cooperates;  I have a quality digital audio recorder with a remote microphone.

 

Ha ha there probably are better ways to do it, yes. It was a last-minute thing, I did the first recording by myself outside my office, and then got a hand from a co-worker. My phone actually records in surround sound by way of it's four microphones, use headphones with the video and you'll hear what I mean. What I was trying to record for the comparison was sound inside the car and outside/behind the car... the Flowmaster had it's characteristic muscle-car rumble that was nearly as loud inside as it was outside, even though I have quite a bit of vibration-dampening and acoustic-foam in my car. The MagnaFlow was quieter from inside the car, with more of its sound traveling away directly from the rear and not being bounced around in chambers inside the muffler.... 

Edited October 4, 20159 yr by BadDog

I'd be interested in hearing what the issue was with the MSD and Pertronix

Well, I tried another coil when troubleshooting my dead MSD 6A box, because when I checked my Flamethrower coil's resistance with my multi-meter, it didn't seem right. There is another thread on that here: 

 I kept the new coil in after removing the MSD 6A box, but at random times over the next week, the ignition would cut out, cut in, cut out, completely die... and then start right back up with a turn of the key a few seconds later. The first of these incidents resulted in a huge backfire that damaged the Flowmaster a little. 

 

The MSD coil was 45,000 volts vs. the Flamethrower's 40,000 volts....

 

So I think that the problem was one of three things:

1) Too much voltage for the Pertronix

2) Too much draw on my car's electrical system

3) The MSD coil's instructions said to mount it vertically, as mounting it horizontally is not optimal. I mounted it in the stock location, so it was horizontal. Maybe it didn't like that too much ;-) It also said to use their marine coil in high-vibration or racing situations. I don't recall the Flamethrower coil's instructions saying anything about vertical vs. horizontal. They are both oil-filled.

From Pertronix Instructions:

"The Ignitor ignition can be used in conjunction with most ignition coils rated at 1.5 ohms of primary resistance on eight cylinder

engines and 3.0 ohms on four and six cylinder engines. For optimum performance purchase and install the recommended

Flamethrower high performance coil."

 

When it says 3 ohm coil for 6 cylinder, that is if you bypass the ballast resistor.

If you keep your resistor like I did so my tachometer would work, then you

use the 1.5 ohm Flamethrower coil.

 

The MSD Blaster coil is less than 1 ohm and will not work.

1) Too much voltage for the Pertronix

2) Too much draw on my car's electrical system

To add to lumen's comment, and modify/reconfigure yours - it might have been "too much draw though the Pertronix module".  When you had the MSD "box" installed, you were using an ignition module to control an ignition module.  The MSD module could handle the low resistance coil, the Pertronix probably not.  The electronic modules can overheat and fail, then come back to life when they cool off.

Forgot to say, it's not the "XX,000" volts that matter it's the primary circuit resistance.  As lumens described.

Edited October 4, 20159 yr by Zed Head

To add to lumen's comment, and modify/reconfigure yours - it might have been "too much draw though the Pertronix module".  When you had the MSD "box" installed, you were using an ignition module to control an ignition module.  The MSD module could handle the low resistance coil, the Pertronix probably not.  The electronic modules can overheat and fail, then come back to life when they cool off.

True. I probably wasn't clear on the fact that the low-resistance MSD coil was only installed *after* my MSD crapped out and I wasn't getting any spark. I did the coil swap as a troubleshooting step instead of tapping into the MSD wiring at the various points needed for their troubleshooting instructions....

I put the oval stainless Magnaflow on mine last year. Tight fit but I 

really like the sound. No pre muffler needed. I need to do some

work to get it tucked up inside more. 

The pre-muffler is for drone elimination.  Not so much for noise reduction.  As I understand things.  Anti-resonator.  You'll know it when you feel it, at about 2500 RPM, apparently.