• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

Do Flowmasters hurt performance?

  • Thread starter Thread starter mjh78
  • Start date Start date Dec 3, 2007
Prev
  • 1
  • 2
First Prev 2 of 2

M.P. Cobra Fan

New Member
Aug 10, 2007
19
0
0
Atlanta GA
Dec 4, 2007
#21
  • Dec 4, 2007
  • #21
I have checked for exhasut leaks I have none. Now mine do not sound like what is being described above. Maybe we are all thinking something different but describing it the same? I know what an exhaust leak sounds like, and what to look for. I do not have one.

Like I said, I have had many many cars over the past 16 years. Almost all of them have had after market exhaust of some sort. All of them made some sort of popping upon slowing from higher RPM.
 

DropTopPony

Noob Slayer
Founding Member
Aug 13, 2002
2,570
3
48
south jersey
Dec 4, 2007
#22
  • Dec 4, 2007
  • #22
I don't know if Flows rob power but they aren't the best flowing muffler. I have seen several cars pick up 5-15 rwhp just by switching out the Flows for a set of Borlas or Spintechs etc...but these were all 400+ rwhp cars.
 

lazerred02

New Member
Nov 19, 2004
190
1
0
FT Stewart, GA
Dec 4, 2007
#23
  • Dec 4, 2007
  • #23
04GTMustang said:
my guess would be if other peoples flows are not popping u might have an exhaust leak somewhere. I know ive got a leak somewhere with my exhaust i think its where my xpipe connects to the manifold. but i have a sort of rattle sound around 2k and under when im hitting the gas. its not a ping type rattle. and it pops on decel but im pretty sure all borlas pop a good bit on decel lol.

i would check everything again something may not be lined up properly and ur just not seeing it.
Click to expand...

I know for a fact I don't have any exhaust leaks at all. I don't necessarily think that the sound around 2k is coming from the exhaust, but it could be. Maybe a Cat is coming apart internally
 

BurningRubber

10 Year Member
Dec 6, 2004
1,865
24
58
Dec 4, 2007
#24
  • Dec 4, 2007
  • #24
When the exhaust is cold (or warm, just not hot) tap your fist or hand against the converters and see if they rattle. If so they are breaking up inside.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,167
17,862
224
Massachusetts
Dec 4, 2007
#25
  • Dec 4, 2007
  • #25
SVT32VDOHC said:
I didn't have any popping at all with my Flowmasters. I have had 11 or 12 Mustangs, most having flows, never had popping.
Click to expand...



+1


Both my cars have flow and no popping


When i had MAC on my 5.0, it used to pop when i let off the gas.
 

Mossberg

Active Member
Jul 21, 2003
0
1
36
ATL, Shawty
Dec 5, 2007
#26
  • Dec 5, 2007
  • #26
Yeah, I don't understand the popping either. Mine don't do it even with the off-road pipe.
 

M.P. Cobra Fan

New Member
Aug 10, 2007
19
0
0
Atlanta GA
Dec 5, 2007
#27
  • Dec 5, 2007
  • #27
OK. I heard one today that had an actual popping. It sounded much different then mine. If that was the popping y'all are talking about, no mine does not pop.
 

the_tool_man

New Member
May 30, 2002
17
0
1
Spartanburg, SC
Dec 5, 2007
#28
  • Dec 5, 2007
  • #28
My car has made a popping noise off-throttle since new. When I put Flowmasters on, it just got louder. I like it. I have no leaks, and an otherwise stock exhaust system.

Regards,
John.
 

Mossberg

Active Member
Jul 21, 2003
0
1
36
ATL, Shawty
Dec 6, 2007
#29
  • Dec 6, 2007
  • #29
It must matter if you have original 40s, deltas, or super 40s. The type of midpipe may have something to do with it also. Maybe even the exhaust diameter (2.25" vs. 2.5")
 

hotdog71

Member
Dec 8, 2004
427
0
16
Seattle, Eastside
Dec 6, 2007
#30
  • Dec 6, 2007
  • #30
Hi,

Popping is normally caused by un-burnt fuel being thrown into the exhaust system causing the fuel to explode. I think you'll find it's very common in racing cars, rally cars where full throttle is followed promply by closed throttle and thus the result is popping.

Sounds quite cool really you should try it
 

1Phat5Liter

New Member
Jul 22, 2007
37
0
0
Los Angeles, CA
Dec 7, 2007
#31
  • Dec 7, 2007
  • #31
I ran Flows in all my 5.0s, and i used to get popping usually after letting off the gas after hard acceleration. Also used to get popping after high rpm revs at idle. I liked it
 

tank_567

Active Member
Mar 19, 2007
731
26
29
Raleigh, Nc
Dec 7, 2007
#32
  • Dec 7, 2007
  • #32
DropTopPony said:
I don't know if Flows rob power but they aren't the best flowing muffler. I have seen several cars pick up 5-15 rwhp just by switching out the Flows for a set of Borlas or Spintechs etc...but these were all 400+ rwhp cars.
Click to expand...

I lost 8rwhp after installing flows with dumps on my car. I dyno'd at 187 stock and after I had the flowmaster 40s with dumps I had the car re-dyno'd the same day and made 179rwhp and I gained 5rwtq.
 

d98gt

Founding Member
Mar 14, 2002
4,505
59
204
SE Texas
Dec 7, 2007
#33
  • Dec 7, 2007
  • #33
That is compared with stock mufflers?
 

tank_567

Active Member
Mar 19, 2007
731
26
29
Raleigh, Nc
Dec 9, 2007
#34
  • Dec 9, 2007
  • #34
yeap, I just had some flows welded in and lost power
 

99MustangGTVert

New Member
Oct 17, 2007
19
0
0
Dec 9, 2007
#35
  • Dec 9, 2007
  • #35
No popping here. Oh wait popping's cool, race cars do it, oh yeah mine pop, mine pop. LOL.

Oh wait, Ive got Violators.

HAHAHAHAHHAHAHAHA
 
Prev
  • 1
  • 2
First Prev 2 of 2
You must log in or register to reply here.

Similar threads

G
Quiet my 2015 GT on the cheap
  • gsrblack
  • Feb 12, 2025
  • 2015 - 2023 (S550) Mustang -General/Talk
Replies
6
Views
725
2015 - 2023 (S550) Mustang -General/Talk Apr 16, 2025
gkomo
Engine Suggestions on an engine rebuild. Stock cam/GT40Ps or aftermarket on both for a fun weekend driver?
  • MadSquirrelTech
  • Apr 28, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
23
Views
593
Fox 5.0 Mustang Tech May 7, 2026
MadSquirrelTech
Place to Avoid: Jamison Auto Group in Gulfport, MS
  • D Durden
  • Oct 20, 2025
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • 2 3
Replies
45
Views
2K
1965 - 1973 Classic Mustangs -General/Talk- Feb 4, 2026
nickyb
Progress Thread Progress Thread- From6to8's 1994 Cobra Supercharger install
  • from6to8
  • Sep 25, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 20 21 22
Replies
420
Views
9K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- May 6, 2026
from6to8
S
Upgrade Advice on an 89 GT Convertible NJ
  • SteakDad
  • Apr 17, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
10
Views
818
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 18, 2025
limp
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?