Flowmaster mufflers

redchev · September 25, 2003

I currently have a 70 series big block muffler 3" in dual 2.5" out. The truck is a 1998 with a 350 and the pipes exiting the rear of the truck on each side of the hitch. I bought a 40 series delta flow but I a'm afraid it will be too loud. Has anyone had experience with both of these mufflers and can advise if it's worth extending my current pipes? I just want my truck a little louder. I hate to cut up a 3 month old exhaust system to find out there is no change or end up getting pulled over for being too loud.

Shaners · September 26, 2003

The 40's are pretty loud, but are legal and won't cause too much "disturbance of the peace" as long as you don't tromp on the gas all the time... Maybe the 50 series would be an option, it is a little bit more middle of the road.

Greg · September 26, 2003

My son has the 40 delta flow on his 4.3 S-10 and it's just right.

Butch 02 Denali · September 26, 2003

Had a friend that put the 40 series NOT delta flow on and it was way loud! He got a couple of 12" long 2 1/4" glasspacks and welded them in after the Muffler, one on each outlet. It sounds great now, made a big difference!

Butch 02 Sierra Denali

timk49 · September 26, 2003

It was the noise inside the cab that made me go to a quieter series muffler. I got tired of trying to hear my wife talk to me on the trips down the highway. She drove my truck to the store a couple nights ago and I hadn't heard my truck from the outside for quite a while. The truck rumble was nice. I've got the 6.0 motor and installed a flowmaster P/N 530513. That muffler is a direct match for the 2003 setup. It isnt nearly as loud as the Thorley headers I had on my 95 Silverado with the 5.7 but I like quiet cab better.

Silverado 4x4 · September 26, 2003

Go with the 40 series. You'll be happy you did!

Stomper · September 28, 2003

I have two (3" in and 2 1/2" out) non-Delta Flow 40-Series mufflers on my 2003 1500HD and it sounds great. It is pretty load but its a good sounding load, real deep low rumble. I had the 3" single in 2 1/2" dual out Delta Flow 40-Series on my old 1500/5.3L and it wasn't very load at all. I don't know if the 6.0L motor puts out alot more noise or if the Delat Flow part of the muffler made it that much more quiet.

Just my 2 cents;

If I were you I would go with the Delta Flow 40 Series for sure and if you think you want it real load go with the non-Delta Flow 40-Series.

elboberino · September 28, 2003

I've got the exact same mudffler you have, original 40 series. On the 5.3 it sounds beautiful. On the 350 it sounds even better IMO. I had it on a '95 burb and it sounded awesome on it. I wanted it loud though so it sounded good to me. My cousing has the 70 series on his '00 and it seems pretty quiet compared to the 40 series. The noise difference in the cab is pretty great. The 70 series is a lot quieter. As for the noise issue outside of the cab, it depends where you live. I got pulled over once but the cop took one quick look under my truck, saw I had a muffler, and said sorry and left. But hey, that's Arizona. Good luck with the 40 series, I recommend them to everyone i hear talking about mufflers.