Need advice. Flowmaster 40 compared to 70 series

[splash]

I have a pontiac 350 putting out 450hp. It Has "Dougs" Headers. I opted for a 3" inch exaust through Flowmaster 40 series dumped at the axel. It is way loud. Sounds good but too loud for normal street driving. I'm thinking of going with the 70 series to quiet it down. Any thoughts or suggestions?

[zbugger]

Suggestion? That 3" exhaust is too big. Also, that's part of the noise issue. You could also try running 2.5" pipes the rest of the way back too. That would quiet it down.

Here's an example. I have 2.5" 40 series Flowmasters under my Camaro. I had it coming right out of the muffler, in front of the rear axle. Loud as hell and I loved it. I drove around setting off car alarms everywhere. It was fun to me. Well, I wound up putting tail pipes on it all the way back to the bumper. I had the toughest time setting off alarms after that. It was still really loud, but only when I REALLY got on it. the car even felt better off the line too. My neighbor almost the exact same exhaust on his '65 Mustang. My car has a catalytic converter, and his car was true duals with 2.25" pipe. Who's was louder? Mine was. I shook his house more, and his car was in his driveway next to the house while mine was on the street about 20 feet away.

Anyway, if you want it really quiet, you could get the 70's. Honestly, I'd say to run tail pipes, with a smaller diameter, and swap to a 50 series muffler.

[chicane67]

Suggestion? You could also try running 2.5" pipes the rest of the way back too. That would quiet it down.

Anyway, if you want it really quiet, you could get the 70's. Honestly, I'd say to run tail pipes, with a smaller diameter, and swap to a 50 series muffler.

Exactly my thoughts.........

[bdoobie69]

I just got my exhaust done up this weekend. I got 40 series flowmasters with 2-1/2" pipes. I have an x-pipe installed an the sound is awesome. I am actually surprised that for a 40 series, it actually is not outrageously loud. It still has all of the 40 series sound qualities, just without the interior resonance and loudness. I would definately recommend it.

[Procharmo]

Just finished installing 2.5" Flowmaster 44s on a 355 SBC 1977 Camaro. I had 2 blowing turbo mufflers and just cut them out and replaced them. Its not louder till you get on it, just deeper. I still can hardly hear them inside over the Procharger whine and bypass gushes but from the back its deep and crackely. Definately not big block dual 4" or 5" open header loud. OK for the street.

Will see how it goes before considering 3inch side exit through the rocker panel !!!!!!

[whytry]

I agree with Zbugger on this one, add some tailpipes in 2.5" and see what you think. Do you have an X-pipe? That will help quiet it down some as well. I would do those 2 things 1st. The tailpipes will help alot, right now you are also getting frequency resonance from the exhaust dumps as well, adding to the noise. If you get the tailpipes added it will also increase the distance between the ground and the exhaust exit position which will cut down on noise. Plus more than likely you will get rid of the typical 40 series turndown drone....

[impalatpi66]

i switched my flowmaster super 40's on my 66 impala to magnaflows 4x9 case. The magnaflows are only loud at WOT. Cruising and at idle it has a nice rumble.