I don't contribute very often as I typically don't have anything to add, but, I had a new Flowmaster American Thunder muffler installed today and I gotta say - it exceeded my expectations.
As you know, the 2005-2007 V6 muffler/exhaust sounds a bit tame at best. I wasn't out to try and fool anyone into thinking I had a GT, but I saw a recent episode of some show on the Speed channel and they mentioned that the Flowmaster not only had a marked increase in HP (small, but measurable), but also a measurable increase in fuel economy (again, small, but measurable).
So I bought myself an early holiday present, researched, found the best price from an ebay seller ("net-parts-express"; $169.95 includes free FedEx ground shipping - compared to $270 from the Flowmaster site). Got it in 3 days. Had Meineke install it for $75- (and give me the old one back, in case I sell one day and the new owner wants the stock muffler for some unknown reason).
The thing sounds great! A nice low rumble at idle, and that classic powerful tune through the middle RPM's. When you gas it, it really comes to life, although I do admit the pitch is a bit higher than I had hoped when you're really stepping on it (coming close to a tuner fartcan, but a few steps back). So all in all I give it 8 out of 10 stars - for being available at a good price, a quick & easy swap (less than an hour), and sounding pretty fantastic.
Matter of fact, on my way home I pulled into a gas station to fill up and LO - in front of me was a white 2006 GT (mine's a white 2006 V6). He started up and pulled away and I could tell we sounded pretty much the same.
A good investment, and I will spare my neighbors excessive revving - it really sounds like a muscle car now!

 

+1 for Flowmaster!

I'm switching to duals now, but I've got a single Flowmaster AT on my Mustang right now and they sound pretty damn good!

You'd definitely notice a lot more people looking at you when you walk on it now.

I was once leaving a parking lot and stomped on the gas, and a guy walking in a crosswalk about a block and a half in front of me stopped in the middle of the street and turned around to look at where all the noise was coming from.

For a single muffler, the Flow AT does a very nice job.

 

Hah - yeah - definitely some reaction to the sound! I've always gotten at least one comment per week, people just love the design of the 2005+ Mustangs it seems (and I'm still happy with my purchase, some 18 months later - - can't be said for any previous car I've owned). But me brapping it all over town this evening, showing off my new sound, certainly added to it I am sure. Best bang for the buck, in my opinion. Next on the list are a new cold air intake, some 1/4 window louvres, billet grilles (flat back, if i can find the things - proving impossible), sequential tail light kit, and still need to de-badge (remove front pony, re-stripe, remove door bumper guards). tinting, new stereo should round it out. Vroom vroom!

 

haha, get out the check book.

The Mustang is an absolute money pit. I love it!

 

I also have flowmasters but I have the Super 44s. One of my favorites is that I am now able to set off car alams by just starting her up. [/align]

 

thats the best feeling...i do that constantly with my magnas too

 

OIIIIO, are those Roush 1/4 window louvers, or something else? Pretty much what I am looking for, style-wise.
Weird - I heard a couple car alarms going off as I drove by - I'd be proud if it were my Flowmaster!

raubt, yeah, once you start you can't stop. i'm just starting...pray for me (and my bank account).

 

No, got them from http://wheelskin.com/mustang-louvers...-spoilers.html


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glad you like your flowmaster...watch out for that mod bug..haha

 

Perfect - that's actually the same source I found earlier via eBay and clicked through to their website - seemed to have the best prices on quality painted items, good customer feedback, and a nice selection. Will likely use them for the 1/4 window louvers, and mirror covers. Thank you.