Flowmaster cat back?

[slovcan]

Hi folks,

It's hard to believe I can't see this system talked about here https://www.holley.com/products/exhaust/exhaust_systems/flowmaster/american_thunder/parts/17224 . I was sort of set on using a Gibson CFT muffler, but it seems I'd have to jump through some hoops to get the same dual inlet/single outlet configuration. I'm sure a muffler shop could put it together, BUT I'd prefer a bolt-on set up rather than weld on, because I MIGHT need it to be reversible in the future (to pass the import conformation inspection in another country).

My original 24 year old muffler is still good, but using it for another salty winter might take a lot of life out of it at this point. I'd also like to stick with stainless steel so everything will last for another 24 years, although I might not...

Anyway, then I saw the Flowmaster system I linked above. I'm not a Flowmaster fan and that system has a stainless steel muffler, but only aluminized tail pipe. I've heard iffy comments about the Flowmaster quality these days. Also, I don't want it obnoxiously loud and droning. I know, the Gibson would be as loud as the Flowmaster, but I am hoping the 50 Series Big Block won't be overly loud in everyday life.

So, has anybody here used this system and not yet written about it? Do you like it or was it a mistake?

Thanks,
Glenn

 

[1997]

i put the cat back on my 95 about 2yrs ago, not a fan.
Too loud, drones, heat shield rattles and didn't fit very well, imo.
it replaced a dyno max cat back system which lasted a long time, was quieter and fit better.
should have replaced it with that, but couldn't find one, hence the flowmaster.

 

[Schurkey]

I installed a different Flowmaster cat-back system (Force II, long discontinued I think) onto my '88 K1500 in the early 2000s. The muffler was never as quiet as I wanted, but the whole muffler/pipe system fit great.

By 2015, it was totally rotted out and had been rusting through for a couple years before I actually removed it when it came apart (outright broke) and fell down. So the Flowmaster pipes and muffler were "good" for something like ten or twelve years and 70K miles.

You must be registered for see images attach

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Aluminized steel stinks for exhaust work.

 

[slovcan]

i put the cat back on my 95 about 2yrs ago, not a fan.
Too loud, drones, heat shield rattles and didn't fit very well, imo.
it replaced a dyno max cat back system which lasted a long time, was quieter and fit better.
should have replaced it with that, but couldn't find one, hence the flowmaster.

Hi 1997,

Thanks for your answer - even if it wasn't quite what I had hoped for ;-) . Can you remember what series Flowmaster muffler you put on? 50 Series Big Block? About the Dynomax, was it also a dual inlet/single outlet?

Thanks,
Glenn

 

[slovcan]

I installed a different Flowmaster cat-back system (Force II, long discontinued I think) onto my '88 K1500 in the early 2000s. The muffler was never as quiet as I wanted, but the whole muffler/pipe system fit great.

By 2015, it was totally rotted out and had been rusting through for a couple years before I actually removed it when it came apart (outright broke) and fell down. So the Flowmaster pipes and muffler were "good" for something like ten or twelve years and 70K miles.

You must be registered for see images attach

You must be registered for see images attach

Aluminized steel stinks for exhaust work.

Hi Schurkey,

10 years is OK with me. Still shocked the original is 24 years old! I suspect your muffler and pipe was aluminized. The muffler in the kit I was looking at is stainless. Still, 10 years is fine.

Thanks,
Glenn

 

[1997]

Hi 1997,

Thanks for your answer - even if it wasn't quite what I had hoped for ;-) . Can you remember what series Flowmaster muffler you put on? 50 Series Big Block? About the Dynomax, was it also a dual inlet/single outlet?

Thanks,
Glenn

here's what i used, single in, single out. Flowmaster 17147 - Force II Cat-Back System - 3" Tubing - Single Side Exit - 70 Series Big Block II Muffler

 

[slovcan]

here's what i used, single in, single out. Flowmaster 17147 - Force II Cat-Back System - 3" Tubing - Single Side Exit - 70 Series Big Block II Muffler

Well, that sure is disappointing. Pretty much like the kit I linked but that was for the 454 Extended Cab Long Box. Both the 70 and 50 series big block mufflers are supposed to be mild-stock exterior/mild interior sound. And yours is loud and drones. Yup, disappointing. Thank you, 1997!

 

[Frank Enstein]

Hi folks,

It's hard to believe I can't see this system talked about here https://www.holley.com/products/exhaust/exhaust_systems/flowmaster/american_thunder/parts/17224 . I was sort of set on using a Gibson CFT muffler, but it seems I'd have to jump through some hoops to get the same dual inlet/single outlet configuration. I'm sure a muffler shop could put it together, BUT I'd prefer a bolt-on set up rather than weld on, because I MIGHT need it to be reversible in the future (to pass the import conformation inspection in another country).

My original 24 year old muffler is still good, but using it for another salty winter might take a lot of life out of it at this point. I'd also like to stick with stainless steel so everything will last for another 24 years, although I might not...

Anyway, then I saw the Flowmaster system I linked above. I'm not a Flowmaster fan and that system has a stainless steel muffler, but only aluminized tail pipe. I've heard iffy comments about the Flowmaster quality these days. Also, I don't want it obnoxiously loud and droning. I know, the Gibson would be as loud as the Flowmaster, but I am hoping the 50 Series Big Block won't be overly loud in everyday life.

So, has anybody here used this system and not yet written about it? Do you like it or was it a mistake?

Thanks,
Glenn

Based on one of the applications for the system outlined on your link here are the results of a search @ Summit Racing.

1998 CHEVROLET C3500 Chevy big block Gen VI Exhaust Systems Exhaust Systems & Kits Exhaust Parts & Accessories | Summit Racing

Find 1998 CHEVROLET C3500 Chevy big block Gen VI Exhaust Systems and get Free Shipping on Orders Over $109 at Summit Racing!

www.summitracing.com

The Flomaster American Thunder system is the loudest system Flowmaster sells. The Gibson claim to fame is quiet power.

A glasspack muffler makes a great resonator if the system you choose is too loud/drones. The larger the muffler case (volume) the quieter it can be and generally flows better as well.

Loud doesn't equal fast!

Use Band Clamps (butt style NOT lap style) so the system can be easily removed. Lap clamps are for use with spiral flex pipe and won't clamp a muffler tight enough for a leak free seal. Welding is the best seal but is kinda hard to remove later.

I prefer and use the Summit brand clamps because they use a nut to tighten vs. the Walker that use bolts threaded into an aluminum block. Either way use anti-seize on both the bolts and pipes if you ever want them to come apart later without using a Sawzall or torches.

Further I paint my exhaust systems right after installation with this.

VHT SP106 VHT FlameProof Coatings | Summit Racing

Free Shipping - VHT FlameProof Coatings with qualifying orders of $109. Shop Paint at Summit Racing.

www.summitracing.com

Two of that part number will do the whole system. I prefer that color because of the high metallic content, and after curing it looks like new aluminized pipe rather than gaudy barbecue aluminum/fake chrome paint.

For best results paint the system right away after the first test drive. You will need to drive for maybe an hour before painting to burn off all the oils from the pipes and muffler.

When the system cools, disconnect the battery, wipe down the system with solvent (I use lacquer thinner), mask off the bottom of the truck with aluminum foil (hence the battery disconnect) and paint the system following the directions on the can. Light coats are the rule! Heavy coats will flake off. DO NOT paint the catalytic converter or the 02 sensors!

The paint us worthless until cured and comes off like dust on a moth's wings. Start the engine and let it idle until the paint JUST begins to smoke. Shut the engine off and let it cool. After it cools do this again. It may take as many as 4 heat cycles to cure the paint. Then do another hour of driving to make sure the paint is cully cured.

I painted the system on my 77 Suburban and 18000 miles and 1 year later (in Ohio) it still looked new.
Ditto for my 1982 Yamaha 1100 but that went 10 years and 60,000 miles (rode it 12 months one of those years) and it still looked good!

 

[slovcan]

Based on one of the applications for the system outlined on your link here are the results of a search @ Summit Racing.

1998 CHEVROLET C3500 Chevy big block Gen VI Exhaust Systems Exhaust Systems & Kits Exhaust Parts & Accessories | Summit Racing

Find 1998 CHEVROLET C3500 Chevy big block Gen VI Exhaust Systems and get Free Shipping on Orders Over $109 at Summit Racing!

www.summitracing.com

The Flomaster American Thunder system is the loudest system Flowmaster sells. The Gibson claim to fame is quiet power.

A glasspack muffler makes a great resonator if the system you choose is too loud/drones. The larger the muffler case (volume) the quieter it can be and generally flows better as well.

Loud doesn't equal fast!

Use Band Clamps (butt style NOT lap style) so the system can be easily removed. Lap clamps are for use with spiral flex pipe and won't clamp a muffler tight enough for a leak free seal. Welding is the best seal but is kinda hard to remove later.

I prefer and use the Summit brand clamps because they use a nut to tighten vs. the Walker that use bolts threaded into an aluminum block. Either way use anti-seize on both the bolts and pipes if you ever want them to come apart later without using a Sawzall or torches.

Further I paint my exhaust systems right after installation with this.

VHT SP106 VHT FlameProof Coatings | Summit Racing

Free Shipping - VHT FlameProof Coatings with qualifying orders of $109. Shop Paint at Summit Racing.

www.summitracing.com

Two of that part number will do the whole system. I prefer that color because of the high metallic content, and after curing it looks like new aluminized pipe rather than gaudy barbecue aluminum/fake chrome paint.

For best results paint the system right away after the first test drive. You will need to drive for maybe an hour before painting to burn off all the oils from the pipes and muffler.

When the system cools, disconnect the battery, wipe down the system with solvent (I use lacquer thinner), mask off the bottom of the truck with aluminum foil (hence the battery disconnect) and paint the system following the directions on the can. Light coats are the rule! Heavy coats will flake off. DO NOT paint the catalytic converter or the 02 sensors!

The paint us worthless until cured and comes off like dust on a moth's wings. Start the engine and let it idle until the paint JUST begins to smoke. Shut the engine off and let it cool. After it cools do this again. It may take as many as 4 heat cycles to cure the paint. Then do another hour of driving to make sure the paint is cully cured.

I painted the system on my 77 Suburban and 18000 miles and 1 year later (in Ohio) it still looked new.
Ditto for my 1982 Yamaha 1100 but that went 10 years and 60,000 miles (rode it 12 months one of those years) and it still looked good!

Thank you, Frank. You have a lot of excellent information there. I was going to use band clamps when I was going to go the Gibson route. I planned to slather some Permatex muffler sealant on the pipes under the clamps, because I wasn't sure that type of clamp could give a leak free seal. Then I saw this FM system and figured it would take away the "multi-adapter and pipe" result I was likely to get by putting on the Gibson. This one looks like the existing exhaust pipes slip into the muffler inlets, but OD/ID band clamps might still be the best option if I can get the right sizes.

I want reduced restriction/backpressure and really don't like fibreglass or other material matting in the muffler cases. That's why I was hoping to find something in a chamber type muffler, but not crazy loud. In listening to both the Gibson CFT and FM 50 and 70 Series on videos - even through good speakers - the Gibson didn't sound any quieter than the Flowmasters. Then again, with the variations in camera quality, it is hard to compare the resulting sound.

I was going to paint the joints, too, but now I know the best paint to use and why it is the best.

Thanks again,
Glenn

 

[Frank Enstein]

You're welcome!

The American Thunder systems typically use a 40 series muffler. Much louder than the 50 or 70 series mufflers.

Dynomax UltraFlow and Magnaflow mufflers use stainless steel wool and ceramic packing. Lasts much longer than fiberglass.

If you can wait I recommend going to a car show and find a car you like the sound of and ask the owner what mufflers they used.
personally I like a Dynomax Large Body (Hemi) Super Turbo with a Glasspack for a resonator after. Nice rumbly tone but quiet.