Flowmaster

[timk49]

Today I finally got rid of the soft sounding stock muffler and installed a Flowmaster Model # 530513. This one is made for the 6.0 motor and it fit and sounds great.  There is something about that low rumble of the gas motor that makes me feel good.

I know the Duramax diesel is an awesome engine but I could never own one because I'd miss the thunderous roar of that V8 when I push that pedel to the floor.

[Shaners]

Is that a dual-in/dual-out direct fit muffler?  Is there any resonance in the cab?

[Black02Silverado]

A friend of mine has a dual in single out 50 series and it is fairly loud inside the cab. I don't have the part number for his, sorry. I feel the 70 series would be much quieter. I know the 5.3 isn't the 6.0 but on mine it is quiet. Seventy series that is.

Yea there isn't anything like a good sounding gas engine.

 

 

 

[cdhd2001]

I am running a Flowmaster 70 series BBII muffler, dual 2.5" in dual 2.5" out.  Very aggressive sound outside.  Slight resonance inside between 1,600 and 1,800 rpms.  Sounds similar to my 1994 350 with dual glass packs.  :thumb:

[timk49]

This model is the dual in single out model . I really don't know which series it is. it matches up to the two inlet pipes perfectly and a short section of pipe comes with it and ties right back into the original exhaust tip.

It sounds good I don't mind the additional noise I like it. I don't hear a resonance in the cab but it is louder than stock. I wouldn't have bought it if it didn't sound strong.

 

Shaners, I saw in a post of yours that you polished the exhaust tip. What did you use to get it so shiney.

[Shaners]

Shaners, I saw in a post of yours that you polished the exhaust tip. What did you use to get it so shiney.

I originally used NeverDull wadding and elbow grease.  The weather has been terrible this winter so I haven't touched it for at least 6 months.  When Spring comes I will probably scrub it real good with an SOS pad and then polish it up with NeverDull again.

[20012500]

timk49 - would there be any way to put a sound clip on the web so that we may listen to the exhaust.  I am thinking of buying this system but I am not sure of all the talk I have heard about the noise in the cab @ the 1,800-2,000 rpm range.

Even Flowwmaster said that it might be on the verge of too loud.  I don't mind it being louder, as long as it is not annoying loud.  Thanks for your help

[cowboy02]

Even Flowwmaster said that it might be on the verge of too loud.  I don't mind it being louder, as long as it is not annoying loud.  Thanks for your help

 

If your worried about inside the cab noise I would go with a magnaflow exhaust.  You get the deep rumble on the outside without the in-cab resonance......  A wise man on this forum once told me..........

 

Your going to have resonance at 1600-2000 rpm no matter what as something vibrates at the rpm, the stock muffle (Should I say trash can) is so big that it muffles that sound and spreds the vibrations out so you don't hear it.  Crawl under your truck and have someone rev the engine to 2k and you'll feel the vibrations, past 2k it stops

 

The magnaflow has baffles inside the mufflers I believe (Don't quote me) and this takes the noise down in the cab...

 

However if you stop on it :thumb:  :thumb:

[Professor]

20012500.

 

I installed a cat back on my truck. I have a 2500LD 6.0. The Flowmaster Part Number is 17325.  It included a 3in tail pipe and Muffler. The muffler is a dual 2 3/4 inlet with a 3in outlet. It is a special 70 series big block II muffler not sold separately.  Depends on your definition of loud. I can’t hear the tires anymore but I would not call it loud at all. It is much louder than the 3in inlet - 3in outlet 50 big block series I had on my suburban as well as the twin BBs  (2.5) on my 6.2 NA Diesel pickup.  It actually sounds very good.

 

The complaint I have is that it seems to have killed the low end torque. Previously the throttle was so touchy you had to use a bit of care driving it in rain. The change was so drastic I was able to run a 16.64 time with my GTech with almost no spin at all IN THE RAIN! It does fill a bit better in the 3500 to 5500 range, but I’m more interested in towing and mileage. I was hoping for an improvement in the 1500 to 2500 range. I think milage has suffered to the tune of about .5 to .8 mpg

 

 

The Gtech is new so I need to do a few more tests with it. I will then establish a baseline and have a stock muffler hung back on it. I have heard the HD trucks have a better muffler than the LD. The LD has dual 2 ¾ inlet with a 2 ¾ outlet. I was told the HD has a dual 3 in and a 3 outlet.  I may have them put one on a stock HD muffler.

 

I’ll then evaluate the changes and decide which muffler to keep. The Gtech should tell give me some good info. Wish I would have had it prior to the change!

 

Hang on to your old muffler, I may need to buy it.

[Shaners]

The complaint I have is that it seems to have killed the low end torque.

 

I was told the HD has a dual 3 in and a 3 outlet.  I may have them put one on a stock HD muffler.

 

 

Hang on to your old muffler, I may need to buy it.

I can't afford any of the low end torque loss that you have noticed..

 

I know my stock muffler on my HD is a dual-in/dual-out and it sure looks like 3" on all the pipes.  The "Y" pipe is about a foot or two behind the muffler and then it goes into a 3 1/2" pipe.

 

If I ever get another muffler, then I will keep the stock one...

[Professor]

Took the Flowmaster off today. It really picked up the low end. Roads were still damp so I could not get any runs with ther gtech. It will break the tires loose easily on wet pavement again. It will be interesting to see how much comes off the top.

 

They muffler we put back on was off of a HD. Two inlet and two out Y'd into one tail pipe. Looks like a 3.5 in tailpipe.

[Shaners]

They muffler we put back on was off of a HD. Two inlet and two out Y'd into one tail pipe. Looks like a 3.5 in tailpipe.

MAybe GM really did their homework and the stock exhaust is what makes the best usable power???

[Professor]

Shaners you are right they did do the homework. I think I'd have to change the cam and custom program the ecu to take advantage of the muffler.

 

 

I was able to get a run today. This was only one run compared to about 6 with the flowmaster.

 

 

60' -.19

330' -.3

1/8 -.446

1/8 +2.77 mph

1000' -.564

1/4 -.645

1/4 +2.36 mph

 

Looking at the hq - tq figures I appear to gain about 30 hp and 40 ft/lbs @ 3700 but it goes down as the rpm goes up.

 

I need to make a couple more runs. The gtech did not display the hp-tw below 3750. I can usually get it to record 2750 up about 3 out of 6 runs. I'm interested in what it looks like at 2750. Seat of the pants confirms what the Gtech is showing. Hope to see the MPG go up a bit as well.

 

Anybody want to buy a month old Flowmaster cat back?  

[Bud]

20012500.

 

I installed a cat back on my truck. I have a 2500LD 6.0. The Flowmaster Part Number is 17325.  It included a 3in tail pipe and Muffler. The muffler is a dual 2 3/4 inlet with a 3in outlet. It is a special 70 series big block II muffler not sold separately.  Depends on your definition of loud. I can’t hear the tires anymore but I would not call it loud at all. It is much louder than the 3in inlet - 3in outlet 50 big block series I had on my suburban as well as the twin BBs  (2.5) on my 6.2 NA Diesel pickup.  It actually sounds very good.

 

The complaint I have is that it seems to have killed the low end torque. Previously the throttle was so touchy you had to use a bit of care driving it in rain. The change was so drastic I was able to run a 16.64 time with my GTech with almost no spin at all IN THE RAIN! It does fill a bit better in the 3500 to 5500 range, but I’m more interested in towing and mileage. I was hoping for an improvement in the 1500 to 2500 range. I think milage has suffered to the tune of about .5 to .8 mpg

 

 

The Gtech is new so I need to do a few more tests with it. I will then establish a baseline and have a stock muffler hung back on it. I have heard the HD trucks have a better muffler than the LD. The LD has dual 2 ¾ inlet with a 2 ¾ outlet. I was told the HD has a dual 3 in and a 3 outlet.  I may have them put one on a stock HD muffler.

 

I’ll then evaluate the changes and decide which muffler to keep. The Gtech should tell give me some good info. Wish I would have had it prior to the change!

 

Hang on to your old muffler, I may need to buy it.

If you get to the point that you want a stock muffler, I think I have one that I took off a '99 5.3. If I can get it to you , you can have it. E-mail me at  [email protected]

 

 

Bud

[Professor]

Thanks For the offer Bud. I'm happy with the one off of the 2500HD! I think I'll leave that end of it alone for a while. I may do an Volant airbox and cold air kit and call it done!

 

Thanks again!