Do Magnaflows really make more power?

98V6 K.I.T.T.

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Mar 6, 2001
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Everett, Washington
Of course, there are tons of questions when it comes to exhaust. If I said "what exhaust should I get?" well...we all know how that turns out. When it comes to exhaust I really think the best sounding exhaust is Flowmasters or MAC's with an O/R H. I don't find Magnaflow or Borla to sound that bad, but I'd pass on SLP and Pypes. My question is, do Magnaflows make a substantial power increase over Flowmaster and MAC? Straight thru mufflers tend to be too raspy for me when they get into the upper RPM range, however I don't mind settling for a little sound quality if I get a good amount of power out of it over a chambered. It's either going to be MAC flowpaths and a Mac Prochamber or Magnaflow Magnapacks with a MAC prochamber.
 
Unless your turbod then your talking about a 1-3RWHP difference. If you turbo charged then your talking 30+RWHP....im serious.

Example of how mad flowmasters suck on a turbo car

Guy with a turbo fox had dual 2.5 inch exhaust with flowmasters welded on just a bit bast the headers. car put down 400RWHP. He jacked up the car and saw zawed off the flows. And did another pull, with THAT being the ONLY difference. Car threw down over 480RWHP.

Someone else (mag maybe) did multible dyno pulls on another turbo fox to adverage everything out. Making comewhere in the 400RWHP range. First set was with 2 chambered flows. 2nd set of pulls was with magnaflows.
Car gained over 30RWHP with the magnaflows and that was the only difference....same day, same dyno.

So you can see that magnaflows flow better, but on blown and N/A cars it doesnt sem to help much.
 
My car did pulled 293rwhp with off road h-pipe and 2 chember flow but now with upr cats x-pipe and magnaflow magnapack it only got 277rwhp :shrug:

My car is loosing power and cannot do good at track. I might have to sell my car cause it whistle and cannot pin point where it's comming from, might be leaking some air tho cause of loss in power. I have change all the gasket , iac, egr and alternator thinking that was what making the whistle but no. I gave up on my car and soon thinking about selling it
 
Ummm..... yea! JK

Actually Ive never heard an exhaust making more power other than maybe 1-2hp either way between any of them.

I never liked the Magnapacks but thats me, I do love the sound of the regular Magnaflow catback though.
 
If you still want a good throaty sound try the UPR O/R X pipe with the Magnaflow catback ( not the magnapacks). A buddy of mine had it on his GT and it sounded damn nice, not raspy at all. I was pleasantly surprised at the sound.
 
hotmustang331;7135734 Guy with a turbo fox had dual 2.5 inch exhaust with flowmasters welded on just a bit bast the headers. car put down 400RWHP. He jacked up the car and saw zawed off the flows. And did another pull said:
This is a bad example. A Straight pipe with no muffler will out flow any muffler and thus give more power.

If you believe the marketing hype, all muffler company's mufflers make 10+ HP more then their competitors.
 
If you still want a good throaty sound try the UPR O/R X pipe with the Magnaflow catback ( not the magnapacks). A buddy of mine had it on his GT and it sounded damn nice, not raspy at all. I was pleasantly surprised at the sound.

This is my setup and I think it sounds amazing. I have them dumped but want to add tailpipes.

As for power, I could feel a difference from the O/R X pipe with stock catback to O/R X pipe with dumped magnaflows.
Can't vouch for flowmasters. I don't like the way they sound and they aren't stainless so I won't buy them.
 
Unless your turbod then your talking about a 1-3RWHP difference. If you turbo charged then your talking 30+RWHP....im serious.

Example of how mad flowmasters suck on a turbo car

Guy with a turbo fox had dual 2.5 inch exhaust with flowmasters welded on just a bit bast the headers. car put down 400RWHP. He jacked up the car and saw zawed off the flows. And did another pull, with THAT being the ONLY difference. Car threw down over 480RWHP.

Someone else (mag maybe) did multible dyno pulls on another turbo fox to adverage everything out. Making comewhere in the 400RWHP range. First set was with 2 chambered flows. 2nd set of pulls was with magnaflows.
Car gained over 30RWHP with the magnaflows and that was the only difference....same day, same dyno.

So you can see that magnaflows flow better, but on blown and N/A cars it doesnt sem to help much.

This guy is right! On big blower, cam, or spray cars the same is true! Whenever the amount of exhaust increases (or in the case of turbo backpressure at the DP reducing efficiency) a chambered muffler is just going to choke it even more.
 
My car did pulled 293rwhp with off road h-pipe and 2 chember flow but now with upr cats x-pipe and magnaflow magnapack it only got 277rwhp :shrug:

My car is loosing power and cannot do good at track. I might have to sell my car cause it whistle and cannot pin point where it's comming from, might be leaking some air tho cause of loss in power. I have change all the gasket , iac, egr and alternator thinking that was what making the whistle but no. I gave up on my car and soon thinking about selling it



Different dyno day/different air conditions? Try putting the old stuff on.
 
I think you would love the magnapacks. I had mac flowpaths before them. I actually noticed a small SOTP over the flowpaths. As for the packs being raspy, I don't think mine are raspy at all. I have them parried up with an MRT catted H pipe. Just listen to the clip in my sig below. If your going with an O/R pipe go with the regular magnaflows.
 
This is a bad example. A Straight pipe with no muffler will out flow any muffler and thus give more power.

If you believe the marketing hype, all muffler company's mufflers make 10+ HP more then their competitors.

I gave that example to show how bad flows restrict a turbo car. the other example shows that magnalfows are good for 30RWHP over flows.
That just shows what straight pipes (AKA: cut out) can do for power over mufflers.

No hype, its fact that some mufflers flow better than others. turbo cars are TOTALLY different than N/A and blown cars when it comes to exhaust. I go with what works. Not all mufflers are created equal mang. Blown cars amplify N/A results as Benny eluded to....and that reason is because exhaust flow increases...then your bottlenecks start to show. Anytime you increase flow through the engine your pushing more through the exhaust.

turbo cars amplify exhaust bottlenecks even more so because the exhaust turbine wheel is VERY sensitive to any back pressure or exhaust pulses on the down pipe side. Flows create pulses that go back and tag the impeller wheel...thats why they suck so bad, along with all other chambered mufflers on turbo apps.
 
This is a bad example. A Straight pipe with no muffler will out flow any muffler and thus give more power.

If you believe the marketing hype, all muffler company's mufflers make 10+ HP more then their competitors.

Do you realize how a magnaflow, or most all other "straight thru" style mufflers work inside? It's just a straight pipe with little perforations, then packing around that; it's not about the brand, it's about the design style. You can literally look straight through a magnaflow muffler, or most bassani/borla/dynomax mufflers. A chambered muffler, of any sort, will cause more restriction, period. The more times (more chambers) the exhaust gas has to change direction the more restriction, and accordingly more back pressure.
 
There is a reason I always call them Slowmasters. Magnaflows are a superior design from a perfomance stand point. The only time I recomend Flowmaster stuff is when I know a car needs the back pressure.

IMO Magnaflows sound WAY WAY WAAAAAAAY better then Flowmasters.

Is your car actually a V6 or did you swap to a V8 ? If you are running a V6 I think you should go with a 2 1/4" mandril bent true dual setup with some Magnaflows.

For most V8s' I say 2 1/2" X or H pipe (which ever you like the sound of better) with some Magnaflows. Mandril bent of course.
 
There is a reason I always call them Slowmasters. Magnaflows are a superior design from a perfomance stand point. The only time I recomend Flowmaster stuff is when I know a car needs the back pressure.

IMO Magnaflows sound WAY WAY WAAAAAAAY better then Flowmasters.

Is your car actually a V6 or did you swap to a V8 ? If you are running a V6 I think you should go with a 2 1/4" mandril bent true dual setup with some Magnaflows.

For most V8s' I say 2 1/2" X or H pipe (which ever you like the sound of better) with some Magnaflows. Mandril bent of course.

Well.....I'm in the 4.6 forum for a reason LOL :D . I used to have a 98 V6 when I first joined the board and haven't really bothered to see about getting the name changed since I've been on the boards for a long time. I have an 02 GT right now.

I think I'm going to go for the Magnaflow Catback. Magnapacks although sometimes I think they sound good, I think I'm going to be alittle unhappy and possibly alittle too loud with an O/R pipe for my taste.
 
I wish I remember the link but last year I found a site that compared almost every brand of muffler. Magnaflow came out on top by 1-2hp. I think Mac flowpaths actualy came in second or third and Flowmasters where at the bottom of the list.