Magnaflow Street vs. Stock Catback with LTs

[Fraxum]

For several months now I have been running LTs and high flow cats on my LS3 with the stock catback. At first I was very happy. But over time a few things bothered me:

• At high RPMs there was a very loud slapping sound.
• The LS3 deacceleration pops were very loud
• Overall the sound was raspy and somewhat high pitched.

After listening to many sound clips and other Camaros and Corvettes I decided to make a change. I would add an axle back system and get rid of the giant cans.

I did not want my exhaust to be overly loud and definitely no drone. With LTs you have to be careful if you want to keep the volume low. I enjoy long trips and not waking up the neighbors and my dogs late at night.

So i researched and listened to more clips. At the end I chose the MagnaFlow Street series Axle back. This system is reasonably priced and came highly recommended. The other axle back I considered was the Borla Touring which is also the street GMMP axle back. I chose the Magnaflow because I could find it cheaper than the Borla.

So I ordered it. Several days later the box arrived. The installation went smoothly. I was afraid to cut my mid-pipes too short so I made the first cut with the Sawzall close to the mufflers. Then I mounted the muffler with the extra connector pipe so I could mark the exact spot to cut on each side.

I used lithium spray grease on those pesky rubber connectors to make things easier. Then I made the last two final cuts and put on both mufflers and connector pipes. After that I went to the back of the car and made sure both tips were in the right spot and evenly matched. Finally I tightened down all the bolts.

Fitment was perfect and all the parts looked high quality. The only tight spot was on the drivers side where the pipe came pretty close to the BMR sway bar grease fitting.

After starting up the car I loved the improved sound. Much deeper and less raspy. THen I took the SS out for a long drive to visit my aunt and uncle out by the Mullica river.

My thoughts:

• The MagnaFlow Street is perfect for me with the LTs.
• Great sound all through the rev range. The slapping sound is gone. The MagnaFlows are a bit quieter at full throttle.
• The deaccelertion popping is still there but very muted. Quieter than the stock exhaust without the cats.
• My gas milage seemed to improve a little. I was seeing a 33 mpg average going 55 on a flat road. I never saw numbers like that before. Is this possible? (Edit: Once the car adjusted to the change normal LS3 gas milage returned)
• The car seems a little slower. Maybe this is just beacuse the MagnaFlows are a bit quieter than the stock catback at full throttle. Hopefully this is just an impression. (Edit: After a few long drive the fun is back)

I recommend the Magnaflow Street series for anyone who wants a great sound with LTs while not making big noise.

[Fraxum]

To follow up on this install....

After driving around for a bit I found the Magnaflow install has pulled the exhaust lower and it was up against the rear edge of the tunnel brace. So I went to Lowes and bought longer bolts and a couple boxes of washers. I think it took seven washers on each bolt to get it low enough.

There may be better solutions, but this was simple and cheap.

As far as gas milage goes over time I have seen no real change. I have not replicated that first trip. My car must have been running a bit lean and now the computer has things right back to where they were before the install.

Also the performance is back too. Power shifting into second now brings on the traction control big time. I should really get out to the track to see what it will do.

Now the bad. Drone. It is there. My first rides were with the windows were down and I did not notice the dreaded drone. Now that the weather is cooler and the windows are up the drone is noticeable. The other day I was out with three passengers and the drone was pretty bad. in sixth gear from 50-70 and especially bad going uphill.

Shifting down to fifth is better. With just me in the car it is not quit as bad, but still there.

So what next? Maybe the Helmholtz solution. Or maybe some gears. I still have the LS3 resonators on, maybe they are the culprit.

[shaggy1]

I'm going to be looking for an exhaust when my SS LS3 finally arrives as well. I think that I have decided on a catback system right now and will add the headers in a few months. I'm also trying to find a catback thats quiet at idle and cruise and wont get obnoxiously loud when I add headers and high flow cats. I have been looking at the Corsa catback exhaust and then the Solo Mach X as well, but I'm leaning towards the Solo system since they are appx $750 msrp. I also had a Solo catback on my 2011 vert and it was a good system as well.
Did you keep your stock resonator or did you add an x-pipe?

[Fraxum]

Originally Posted by shaggy1

I'm going to be looking for an exhaust when my SS LS3 finally arrives as well. I think that I have decided on a catback system right now and will add the headers in a few months. I'm also trying to find a catback thats quiet at idle and cruise and wont get obnoxiously loud when I add headers and high flow cats. I have been looking at the Corsa catback exhaust and then the Solo Mach X as well, but I'm leaning towards the Solo system since they are appx $750 msrp. I also had a Solo catback on my 2011 vert and it was a good system as well.
Did you keep your stock resonator or did you add an x-pipe?

Stock resonator. I wonder if you can completely avoid drone with LTs. The Magnaflow Street was supposed to be drone-less. I cannot use a catback since to install it I would have to first cut it. My high-flow cats are extra long.

The stock catback was drone-less. It was the slapping sound that made me switch. Still happy with the Magnaflow Street axleback.

[SGOS252382]

Very interesting that you have drone issues with the Magnaflow Street Catback (not axle back). The Magnaflow Street is the quietest catback out there.

I've been running the Magnaflow Street on my car for over 2 years and drone has never been an issue (I have an L99 A6 with Kooks 1 7/8 headers).

Also, are you guys running the full catback with the resonated X pipe (not the axle back)? The axle back doesn't come with the resonated X pipe (3rd muffler).

[blkevrythng]

I have the magnaflow street and has some guy try to tell me my car was not an SS because it was not loud. I just smiled....why does everyone think louder equals faster or better?

[Fraxum]

Originally Posted by SGOS252382

Very interesting that you have drone issues with the Magnaflow Street Catback (not axle back). The Magnaflow Street is the quietest catback out there.

I've been running the Magnaflow Street on my car for over 2 years and drone has never been an issue (I have an L99 A6 with Kooks 1 7/8 headers).

Also, are you guys running the full catback with the resonated X pipe (not the axle back)? The axle back doesn't come with the resonated X pipe (3rd muffler).

Sorry for the confusion. I have the stock hpipe (hpipe?) from the cats back to the start of the Magnaflow Street Axleback. Since my cats are extra long I did not want to buy a full catback and then have to cut it to install.

This combo:

BFE LTs->Hightflow cats->stock LS3 resonator->MF Street Axleback = drone

Not sure if its the LS3 resonators. No drone at all with stock catback.

The exhaust is deep but not loud except a high RPMs, Then it can wake the dead. But the drone is there, especially with the windows up and a full car.

Thinking of just garage queening the SS and buying a 335i sedan as a DD. But working from home I do not drive that much. Waste of $$.

[NinoSS]

I have the same set up and have a little drone as well. I wonder since the real difference is just the resonated x-pipe, would the volume at cruise be reduced if this was added.

I would be interested in the results of cutting a res x-pipe at the H-pipe location.

BTW, I have the Fat Mat trunk kit waiting to install.

[Snake Slayer]

I run the full catback with no cats and have zero drone. I think the resonated xpipe goes along way to killng the drone. For you guys running the AB, the resonated X cost about $65.00 if you want to repalace the LS3 resonater. BTW I have an L99.

[NinoSS]

Originally Posted by Snake Slayer

I run the full catback with no cats and have zero drone. I think the resonated xpipe goes along way to killng the drone. For you guys running the AB, the resonated X cost about $65.00 if you want to repalace the LS3 resonater. BTW I have an L99.

From what I understand the location of the x-pipe matters. I considered doing this, but didn't want to loose the little power my car makes... Small cam car here...

[mike.nite]

I guess it is very difficult to have LTs without drone. Even with the stock exhaust I noticed a small amount of drone.

When it comes to drone the Magnaflow resonated X-Pipe is one of the best solutions. Had the same issues with my 2010 2LT. The magnaflow x-pipe reduced the drone about 80% and made the exhaust sound even deeper.

If I'll ever notice some kind of drone on my 2011 2SS I'll install a resonated X-Pipe again.

[Fraxum]

Originally Posted by blkevrythng

I have the magnaflow street and has some guy try to tell me my car was not an SS because it was not loud. I just smiled....why does everyone think louder equals faster or better?

[Fraxum]

Originally Posted by NinoSS

I have the same set up and have a little drone as well. I wonder since the real difference is just the resonated x-pipe, would the volume at cruise be reduced if this was added.

I would be interested in the results of cutting a res x-pipe at the H-pipe location.

BTW, I have the Fat Mat trunk kit waiting to install.

Think the Fat Mat will help? I hate to add more weight. I even feel guilty with adding the Amp and Sub in the trunk. But hopefully ditching the manifolds and stock mufflers have evened things out.

[camarohead]

i have a cam and added the magnaflow street axleback for more louder, better sound and it really made my exhaust to tame..went back to the stock catback because it sounded alot better with my cam...the magnaflow street is really to tame.