Hi guys. I was thinking of swapping the stock muffler for a Single in, Dual output Flowmaster 40 series. Do you think I will pick up any more MPG's doing so?

Thanks!

 

no, you won't. May actually lose a tiny bit.

 

FM will flow better than stock, and you should see some increase. Die hard Magnaflow fans give FM a bad name.
The difference between the flow rating of the two brands is so minute its not even funny.
Yes, Magna flow does flow better, but the only way you are ever going to see a difference is in an application with heavy engine modification.

You might not see any increase in MPG for the first few months you have the FM muffler on there just for the simple fact that you wont be able to keep your foot out of it.

 

Won't increase mpg but could cause occasional low end bog. 40 sounds like a soup can full of marbles! Go MF or Borla.

 

really, because i get comments daily on how loud and mean my exhaust is. It's deep and rumbly

 

For the record, I didn't say no because I have a magnaflow. Too much flow can actually hurt low end performance (the scavenging issue); you will get gains in the high end, but driving in a manner that would make use of it will definitely not give you an increase in mpg.

If you want to swap your muffler for better sound, go for it. But don't expect to get a noticeable performance or mpg gain from it. You won't.

 

Congrats!

 

I don't think so...

 

Lemme ask a question that I think will put things in perspective:

If you guys had a car with an honest 780 hp engine, would you select a pair of flowmaster 40 series mufflers to muffle it? How many people with that much power would?

I bet your answer was no. Certainly, if you've seen many cars at all with that kind of power, you haven't found many (if any) that used ordinary street performance mufflers.

Now, divide that power in half and you have our 390 hp. I actually think it's probably a bit over 400 hp, but we'll ignore that for now. See my point? I seriously doubt a single flowmaster 40 series flows any better than our stock muffler. In fact, I doubt it flows as well. Yes, I know, it has flowmaster written on it, so it's made of gold. Likewise for just about any aftermarket muffler. Gotta be better than stock, right?

Our mufflers are not the one that came on your 1982 camaro. They flow like hell. They HAVE to-they're supporting at least 390 hp while being quiet. If you make the mistake of assuming that louder is better flowing, you're making just that-a mistake. Sometimes it is, but not always. If there were ever a case where louder might just be louder, I think a single muffler supporting 390 hp is it.

So, like others have said, get a muffler if you want better/more sound. Just don't expect much if any performance increase or mileage gain.