For the 2003 GT that I'm about to purchase next month (if this damn snow will melt), my Stang mod. specialist (Mustang Magic--NYC) said that it's better to go with the Mac Catback instead of the Flowmaster 40 series.
My main objection is Sound and HP gain. I love the throaty sound of a GT revving up. He said that recently, he dynoed a Stock 1999 or 2001 (I forget) GT and afterward, by using the Mac Catback, it gained 17 HP. He also said that he would have to install the entire Catback because it's to much work and problems just to add the Mufflers because of the welding. Also, he mentioned that Stock, the tail pipes are 2.5 inches; however, with the Mac Catback, the pipes are 3 inches long.
Previously, I had a 2000 V6 and he installed the Mac catback, dual exhaust (Yes I'll admit it, I had and was proud of my V6. I don't want to hear any comments/jokes about driving a 6 cylinder-damnit) As far as cost, he quoted me $429.00--installed.
Okay guys, in a battle of Sound and Power, can the Mac Catback stand up against the Flowmaster 40 series?
GOD BLESS MOM, AMERICA, APPLE PIE, COORS LIGHT, JACK DANIEL AND FORD MUSTANG GT
So your saying that the stock "tips" are 2.5" and the Mac "tips" are 3". Honestly, I like the way the stock tips look. Anything bigger and I wouldn't like it... I've seen bigger ones on there and I perfer the stock look on the tips.
I really don't know How good the MAC catback is going to be, I haven't looked into it too much.
I've heard the MAC's have a RUST problem. Also quality control and customer assistance stinks (to say it nicely). Since you are up in the tri-state area (my original stomping grounds) snow and rusting of vehicles is common place. I would not use a system that is known for rusting even in the best climate conditions. I personnaly don't like the Flowmasters either. They sound like every other southern pickup truck in this area. I feel they are overpriced and do not offer anything but sound. The performance increase is one of the lowest among the cat-backs on the market.
You may want to do a search on mufflers and see what information you can find on here. I know this subject has been brought up in the past and there are many pro's and con's for all different types of mufflers on the market. Here is a website that has some exhaust systems and sound files.
Originally posted by rks'92/5.0 mac quality sucks, the flows will last 3-4 years i have the american thunder system on both of our GT's 1992 and a 2002.
That is totally not true. The MAC comes HTS coated and keeps the system in good shape. Flowmasters on the other hand have been known to corrode and rust very fast and easily. Check out the cat back shoot out in the tech section.
Quote:
AFM Tech Section- Cat Back Shoot-out MAC 2.5" FLOWPATH SYSTEM
This system is impressive at first glance. 2.5" diameter throughout. The tailpipes are triple chromed and look nice. The muffler sections are HTS coated. This coating keeps the pipes in good condition. The system I tested had survived a Michigan winter, the muffler sections looked almost new.
FLOWMASTER AMERICAN THUNDER ( 2 chamber ) SYSTEM
This system, for as widely as it's used really had my expectations up. The system is aluminized steel and corrodes rapidly. I would expect this system here in Michigan to last 3 years tops! If your car is just a racer, the good news is it flows very well. If you enjoy driving your car though, be wary. Drone was the worst of any system tested. Fit was good with only slight adjustment necessary to keep it away from the 245/45/17's in the rear. This system with a stainless steel tailpipe upgrade is the way to go if you have to have flowmaster's. Power felt nearly identical to the Mac system.
As for soundings, i personally hate the flows. I luv the way MAC sounds, but if i were you i would also consider MAgnaflows. I am either havings some MAC or Magnaflow mufflers installed on my 98 gt here in about 2 weeks. Can't wait!!
Originally posted by Bklynstanger . He said that recently, he dynoed a Stock 1999 or 2001 (I forget) GT and afterward, by using the Mac Catback, it gained 17 HP. He also said that he would have to install the entire Catback because it's to much work and problems just to add the Mufflers because of the welding.
a catback kit will barely net a gain on the dyno, 0-5rwhp at best unless you're heavily modded.
My friend has a 94 GT with Mac Exhaust and it rusted out and has holes at the bend and all of that was after 2 years. I purchased American Thunder with Stainless Steel Tips and have been most happy. I haven't had it very long though. Also, that seems expensive for a MAC system. I purchased my American Thunder from Mustangsunlimited.com and paid like $300 with shipping and installed it myself. Didn't take long. However, save yourself the trouble...if you are not welding buy better exhaust clamps, the ones that came with the Flows broke.
FIST
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96 GTPacific Green, deleted rear wing, white face gauges, 35th anv. instrument bezel, Cobra R's with Nitto 555 245/45, MAC Cold Air Intake, MAC Pulleys, American Thunder Flows w/ss tips, 20% tint all windows, Silver GT insert letters, GT Coin holder Cover, Steeda TRI-AX Shifter, w/ Steeda knob and Cobra Leather boot, FFRP lowering "B" springs, bullitt fuel door, relocated front seats, fog light mod.
Look trust me go with just the flows and go to a good shop and just have them welded in your stock pipes are ideal all after market cat backs will rust even the just weld in thr flows and keep your stock pipes. Well how about this if you don't the flows what ever muffler you get just weld them in. Don't let a shop say or someone tell you they are being lazy by wanting to just install a full cat back thats just because it's harder to weld in just the mufflers take it to someone who will do it and your set.
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There was a guy one here, i forgot who but a little while back and he had a Flowmaster cat back and one side of it rusted very very bad, he had to junk the system.
I have the american thunder catback (40 series Delta)on my 02 GT, That I got for $380 @ Summit Racing ..The quality and the fit is great the tip size is the same as stock with the flowmaster name on it and the sound is why I got this exhaust..Not too worried about rust since I dont drive it in the rain. Hardly any drone and I wish it could be little louder. Can't wait to get my catted H pipe to see what it sounds like.. Hope it's alot louder..
I'm a rebel.I know the Mac Catback will not stand up to
the FLOWMASTER (40 series) Two Chamber in sound
and power.Can only be the "The Sound of Flowmaster".
Yes trust me on this just weld in the FLOWS 40's on your stock pipes your set for good and like another guy said DYNO test hardley show much of a gain with a full cat back just weld in the FLOWS and use your money for a nice H or X pipe.
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First, a catback , like quick 4.6 said, is gonna give you just a couple hp. Nothing close to 17 on a stock vehicle.
Second, I see your friends point about installation of a catback being easier than cutting and welding in mufflers. But 430 bucks to do it?? Come on! Its like a half hour job...i dunno, just my .02
Third, I'm very happy with the quality of my Mac h-pipe and catback. My buddy is a MAC dealer and said if anything rusts (which it hasnt) he'd return it for brand new stuff at no cost. Just find someone good to deal with.
Fourth, the stock tips on 99+ GTs are 3 inches. Mac doesnt offer a 3 inch tip unless you get a 3in catback system. Thats like 5-600 bucks. If you go with MAC, you get 2.5 inch tips or 3.5in tips. I like the way my 2.5s look.
Finally, Nothing against the flowmaster guys, but come on....Every stang has em! At least it seems like every one does. I like MAC's distinctive sound. Its deeper...period.
Hope this helps.
Later,
Jason
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99gt vert, CAI, Ford Racing Shortie Headers, MAC 2.5in catback, MAC o/r h-pipe, FRPP alum. driveshaft, March underdrive pullies, sct custom dyno tune, eibach pro-kit, bullitt alum pedals, Cobra Brake Kit, Tokico shocks and struts, PIAA bright whites...FRPP 4.10s!
Updated Exhaust Question: Flowmaster vs. Mac 
