Flowmaster 40 Series

braveheart98 · August 5, 2003

Greetings,

This past weekend I had my new exhaust installed. I'm running duel 2 1/4" pipes into Flowmaster Series 40 mufflers (Not Delta Flow). Then finally out 3 1/2 x 22" tips. The whole week leading up to the install I was looking forward to hearing the new sound. When the muffler shop fired up my truck for the first time I have to admit I was really disappointed. I was expecting the 60"s muscle car sound. Sure not the sound of the cars I remember from my childhood.

I have about 200 miles on since the exhaust was put on. Will these get louder with time? If so how long does it take? I'm not talking about when they rust off either.

vortec4800 · August 5, 2003

Yes they do get louder as they get broken in. Give it a few months and it should increase a bit. I had my Magnaflow muffler installed probably around 6 months ago, and I loved the sound ever since I got it. I remember the day I was driving it home I could hardly hear it. Now its much louder (but not too loud, I don't like em roaring like the flowmasters do).

The moral of my story is after a while it will get louder, don't worry

greyghost03 · August 5, 2003

I've had my Flowmaster 40 series (3" in dual 2.25" out) for about 6 months now. I must say that 6 months and 10K miles later that it is louder! It sounds great now - just like a 60's muscle car, as you say.

I don't know for sure but if you're running true duals w/2 mufflers there might not be as much back-pressure hence lower noise level? Maybe a dual-in dual-out might be louder for your application?

Also, the tips have alot to do with it. The larger the diameter and length, the more "echo" you hear as the act like an echo chamber.

Just my .02! Hope it helps!

bigtruck21 · August 6, 2003

First thing after a new exhaust should be a nice long roadtrip (at least 100 miles) to get everything heated up and broke in for good sound. It will improve in time, just faster with the roadtrip.

Braveheart, with your 2 1/4 pipes did you notice and increase in lowend tq with the 5.3L. I've heard a few people say 2.5's made the lowend drop off a tad. I was contemplating 2.25's instead.

braveheart98 · August 7, 2003

I didn't notice any serious gain in lowend tq. But it doesn't seem to have dropped either. When I picked this size pipe I was just trying to play it safe. I heard some of the same stories of people having lowend power loss. I know I did with my 97 Silverado with the 5.7L. On that beast I was running duel 2 1/2" straights with resonator tips. For the little I lost in the low end the sound sure made up for it. Thought I play it a little more mellow on the 2000 and use some mufflers this time. I know the neighbors are happy with this decision.

gmcjoe · August 7, 2003

I have a Flow 40 (non-delta flow) on my 2000 5.3l GMC. I kept the stock tailpipe diameter, but have the single in/dual out version dumping along side the spare tire.

I love the rumble - check it out click here

BDBWTE · August 8, 2003

Straight pipe the b!tch if you want the noise. Unforunately these new motors lack the compression, cubes, cams, etc. To produce the muscle car lead burning cars of the past had. I admit I wished my sounded like that. The 8.1's sound good with dual straight 3"s and a h pipe dumping out into 4" tips. They sound healthy with real good cackle between shifts like the older trucks had.

elboberino · August 8, 2003

I have the 40 series and it is very nice sounding. It is a single inlet and dual outlet with 2 1/2 in. turndowns on it. Not only is it loud, it is unlike any other exhaust I have seen around here because you can't see the pipes exit the truck.

If you want loud, the closer the muffler is to the cat the louder it should be. I had the same Gibson on for a while that my neighbor had but he shortened the headpipe and made it sound much louder then made the exhaust come out the side. I did the same thing right before getting the flowmaster.

Good luck with it!

chevy38fan · August 17, 2003

I've put about 4 or 5 thousand miles on my Flowmaster 40's so far (non delta flow) and I haven't noticed it being any louder, but then again, i've only driven it from the inside. LOL.. I did let my friend drive it through some soft dirt so I could hear it well without it getting too far away, and it sounded awesome.. completely awesome. its 2.5" piping going in (two mufflers) and 2.5 inch out with 3.25" tips. not sure how long they are, they are probably a foot or so. I didn't notice any loss or gain in low end torque. but I did notice a gain in top end torque. accelerates much quicker to 100 from 60 than with the original muffler on it.

Sandman1 · August 20, 2003

A Flowmaster is not going to change its sound over time. It is a solid structure baffle design. On the other hand Magnaflows which use a flow-through design similar to a glass pack will change (get louder) over time as the packing starts to break down..

mustard man · September 2, 2003

got the 40 series on my 03 sierra 4.8. VERY impressed with the rumble and yes it does get louder over time. almost 10Kmiles on it. very very loud rumble and specially when i hit 5500rpms to just romp on it.

Matador · September 3, 2003

If you don't mind some resonance in the cab, get dual glasspacks with 4" or 4.5" echo chambers (tips). It's a lot louder (and lower) than any Flowmaster system I've heard, but not as bad as straight.