Flowmaster Increased Horse Power?

[Fugitive]

Yo I heard some disturbing news the other day at my local Corvette Club meeting in the Bay Area. A very respected Corvette mechanic and tuner made the claim that Flowmasters don't increase the horsepower at all! I was like What?
Needless to say I could not give him a good argurment becuase I never dydno tested my LT4 after the install but I strongly believe I feel the difference.
Is there any serious study out there that puts the horsepower question to rest among the major brands like Borla, Corsa, Power Efffects, Flowmaster etc? I mean like the same car same dyno that would be the only way to know for sure. I'm curious and frustrated if my local expert is right. Love the sound but I can't imagine why Flowmaster would be bottem of the line?
"I can handle the truth!" Scott

 

[Edmond]

There would have to be an increase in power due to less backpressure. You're not going to get 20 like the manufacturer's claim but you'll get something.

 

[vader86]

You should get around 10, the loss of backpressure allows the engine to more efficiently remove exhaust gases, thereby increasing the HP of the motor.

There was a magazine or a tuner who did the testing, and all the popular catbacks gave 10-13hp on a stock 350.

 

[Fugitive]

That's what I beleive Vader. I notice now I have very little if any back pressure. I removed my resonator and I never hear any back pressure even when I go down hill in second gear. Also I happen to know for a fact that Aluminum transfers heat exceptionally well and is very light. So how could Borla be much better? I know they use TS 304 stainless so it will look nicer but that doesn't mean it will make it go faster.
One thing worth mentioning is I recall when I was first looking for an after market sytem I found one shop owner who refused to even carry Flowmaster becuase they never cut the shops a deal on price. Perhaps that is the reason why our locale super tuner doesn't like em?

 

[Edmond]

Also I happen to know for a fact that Aluminum transfers heat exceptionally well and is very light. So how could Borla be much better? I know they use TS 304 stainless so it will look nicer but that doesn't mean it will make it go faster.
One thing worth mentioning is I recall when I was first looking for an after market sytem I found one shop owner who refused to even carry Flowmaster becuase they never cut the shops a deal on price. Perhaps that is the reason why our locale super tuner doesn't like em?

I believe Borla has that 1 million mile warranty thing right? Once you install Borla or any of the other stainless systems on, that's it, you'll never have to worry about it again. Yes, it will look nicer but it will also be heavier.

Flowmasters are relatively cheap compared to the other systems. It really depends on how much you want to spend. I went with Flowmaster because I couldn't spring $500 for a pair of mufflers. Maybe on the next Vette'...:L

 

[BiZ]

I gained 12 RWHP and 10 RWTQ after the install of my Flowmaster Force 2 system. This graph shows the last 3 mods to my car.

Blue addition of Headers
Red addition of Flowmaster Force II
Green addition of P&P'd top end (Plenum and Injector housings)

The gains are there.

 

[Fugitive]

Right on Biz! That's what I estimated in my mind. Ten rear wheel horsepower which is a major gain! Only difference I removed my Flowmaster resonator it really sounds nice now! Thanks for your input! Scott

 

[oldace84]

I think mine gave me some xtra breathing, and a little more useable HP.
And I love the sounds, like a song.
Good Luck
tony

 

[BiZ]

Right on Biz! That's what I estimated in my mind. Ten rear wheel horsepower which is a major gain! Only difference I removed my Flowmaster resonator it really sounds nice now! Thanks for your input! Scott

Now time for questions:

Did you leave the resonator in place, install the system, and then remove it? Or did you remove it before the install?

Any difference in resonance? (I still can't find the resonance now)

I am going to be running a X-pipe soon. I will let you know if I gain or lose anything. From what I have seen the X-pipe should give me a little more.

 

[Fugitive]

Allright I installed a Froce II Flowmaster system and kept everything for six years. Then last summer I wanted better louder sound so I cut off the Flowmaster resonator. Incredible difference! It sound more like an old V-8 great split sound! It's louder but I like and I did notice and increase in acceleration. How many horses, can't say never dynoed but if I had to guess I would say at least five more maybe eight. Everyone is installing X-pipes now I'm not. I don't like the way they sound compared to a true dual exhaust. They may generate a lot more power but I never seen the data on just the X pipe alone. May be worth doing since your getting rid of the resonator.
Oh snap! Almost forgot I looked inside the Flowmaster resonator and I couldn't beleive my eyes. It had a large baffle right in the middle of it definetly not a striaight through design like the mufflers. Later! Scott