So... I'm kinda old school. I really like the sound that flowmasters have on a healthy engine with headers. I'm doing a 6.0l swap into a 64 nova and would love that sound, but understand that they are detrimental to performance.
How bad are they for performance, and is there another option that gives the same or similar sound without the performance hit?

 

I think the whole Flowmaster choking power is a bit overstated when comparing it to other brands. Sounds like you prefer the chambered muffler sound over the straight through style. I say get it if that's the sound you like

 

There's just something "right" about that sound on a muscle car.

 

I agree man, but something to consider is that these don't produce same sound as the old school stuff. What matters most is how the entire exhaust sounds as a unit. Something like a Flowmaster can drone and be raspy on these cars when combined with other exhaust components

 

Flowmaster makes a ton of different mufflers. They are not all equal. The race series arent half bad if your running duals and really want the flowmaster sound. With duals your running 1 muffler per 4 cylinders so its not as restrictive as running all 8 cylinders through one.

There are much better options but if sound is more important than all out performance go with what you like best.

 

I think Flowmaster's worst offender around here is the crossflow replacement for F-bodies. It's a wonder it flows at all, compared to a normal Flowmaster, most of which flow rather well, IF you get a big enough CASE SIZE. Big inlet/outlets alone won't do it. Just being a Flowmaster does not mean it will ALWAYS flow well enough for your application.

 

What would be a good option for true duals with side exits on a 64 nova (flowmasters)?

 

How big will the pipes be, and how much HP will the engine make? Depending on all the above, there are Flowmasters that will do a very good job.

 

Probably 3" pipes... engine should be 500-525 crank hp and 1.75" primaries on the church boys headers.

 

Look for 3" in/out with 5" thick case, and they should cause NOOOO backpressure! lol

 

Watch this. Steve Brule is straight up and the dyno don't lie. You will be fine with Flowmaster 40 or super 44 mufflers. Its the stock replacement muffler for 93-02 f bodies that sucks *****.

 

As I thought! Good info!

 

Nice!.. I had a 72 El Camino years ago that had a crate 350, headers and flows... not sure which ones... but it sounded great.

 

Hate to admit it but the FM 80 sounds good on a LS1

 

Looks like the super 40's are probably the ones for me.

 

I gained 20 rwhp on the dyno with H/C/I build using a cut out to bypass my flowmaster 80 series muffler.. they definitely don't flow well.. I've heard of many others seeing the same results.. back to back dyno runs..

 

80 Series Flowmasters are for those who MUST have a Flowmaster that WILL fit in a stocker's place. And it IS better than a stock muffler. A little. And it sounds good.

 

When you say better, you mean sound wise, or flow wise, or both?

 

Sounds way better, flows a little better. Not Flowmaster's best work, IMHO.

 

Sound wise and flow wise any aftermarket muffler is going to be better than stock. Here's the thing though...you are not going to see a big difference in power between most aftermarket mufflers, but there can be a big difference in sound. I'm just talking about comparing the mufflers themselves. I'm not talking different catbacks, tubing size, cutouts, etc...