The FACTS are....a Flowmaster will increase your horsepower over your stock muffler. However, there are other brands that will show a larger horsepower increase, usually in the 5 to 8 horsepower range. The Flowmaster muffler can be bought with out buying an entire catback system and installed for about $200 which is a bargain price compared to catback systems. The Flowmaster is also available in a catback system which has a more efficient muffler than the stand alone muffler and will give you a few more horsepower. A cutout bypasses your muffler and will increase horsepower over ANY rear mounted muffler system. The amount of increase will depend on how efficient your muffler system is. The more efficient it is, the less the gain will be. My last car dynoed over 450 rwhp with a Flowmaster and was capable of running in the tens so they can't be too bad. The Flowmaster muffler with installation for about $200 is one of the best bang for the buck mods you can do to gain a few horsepower and make your car sound better. If you don't like Flowmaster then you might consider the Hooker areo chamber muffler will outflow the Flowmaster for about the same money. It is a quieter muffler though.

 

Just out of curiosity.... which one gives better gains, loudmouth or cut-outs...?
which one is louder...?

 

A cutout is a opening in your exhaust system which bypasses the muffler. Since the exhaust gases do not go through the muffler they are much louder as they come out of the cutout. Again, since the cutout bypasses the muffler, the restriction of the muffler is also removed. That is why you gain horsepower with an opened cutout. When the cutout is closed the exhaust flows through the muffler which adds restriction and quitens the exhaust. The loudmouth is unlike any other catback system in that it does not contain a muffler. Instead it uses a "resonance chamber" which looks like a bullet muffler but is completely hollow. Your catalytic convertors act as the mufflers in the system and the "resonance chamber" only deepens the sound of the exhaust. If you use a loudmouth on a car with the cats removed it will have terrible rasp and sound terrible. The loudmoth is the loudest cat back system and actually seems to be louder than a cutout but I suspect that is because of its lower frequency exhaust note. The second loudest would be the Borla system. Power wise the loudmouth and a cutout are about equal. I ran a loudmoth when they first came out and I really liked the way it sounded.

 

Hey Gold Z, thanks for confirming my beliefs.

 

Get the Flowmaster you will love the sound!!

 

Yes it is TRUE, Flowmaster's "crossflow" muffler (80 series) designed specific for our 4th generation F-bodies is definitely more restrictive than most other aftermarket mufflers/systems available for these cars. I've been around these rides for a good few years now and the dyno/track #'s don't lie...

However, they are still better than stock and will hold their own on a modified set-up up to a certain point. They start to become a restriction on cars making 350+rwhp. At that moment in time, either replace your Flowmaster cat-back with a better flowing one or just slap a cutout on their to accomodate for the extra flow. Otherwise, just live with the fact that you'll be down some ponies.

What cracks me up is that everyone claims you'll lose BIG power with a Flowmaster (we'll say using cat-back systems here) as soon as you put it on your new bone stock LT1/LS1, when in reality it'll gain you some power and only maybe make 2-4rwhp at the *most* less than another comparable cat-back system on that same untouched car. But OK, I guess those extra few ponies must mean that your car now sucks since it is running a Flowmaster system! FYI guys, you won't even "feel" that difference at all until the gap is a good 15+ to the wheels!

BTW, comparing the Flowmaster muffler only to the Flowmaster cat-back system is like comparing apples to oranges. Any cat-back system is going to outflow just a replacement muffler on stock pipes.

If you are looking for that classic muscle car rumble, then get the Flowmaster. But if you are more concerned with every ounce of flow, then get just about any other system (as some sound absolutely awesome too)...

Mike

 

I can't speak to the catback, but my dynos show that the Flowmaster muffler essentially flows the same as stock.

Cut out open on a stock muffler gained me ~ 10 rwhp. With the cut out open with the Flowmaster I saw the same 10 rwhp gain.

If the Flowmaster was more efficient to less efficient, I should have seen either less of a gain with the cut out open or more of a gain with the Flowmaster...

 

I've got this catback on my car and have gotten nothing but good complements on it. If you want to listen to your radio while you cruise and don't want everything in your car rattled apart, get the flowmaster. It screams at WOT and with a y-pipe it just sounds even better. I can't wait to get my longtubes. There is a definate rumble to it. I'll try to get a video this weekend and put it on my website along with some pics.

 

I like the sound of flowmaster if I could post sound on my site I would but cant right now.

 

got any pic of installed flowmaster systems and videos??

 

One of our members did a CFD on the Flowmaster 80 series muffler. I'll dig out the pics this weekend.

 

2-4 Horsepower is a pretty big number when a cat-back only makes 8-10 horsepower. But it is very insignificant in the long run except if you like to use the expression "Every little bit helps" and you are not running a Cut-out.
I drove a car with a Flowmaster Cat-back and I really did not like the sound. It was pretty raspy and was too loud for me in daily driving mode. I had a Hooker Cat-back on my LT1 and I loved that cat-back since it was very quite (almost unnoticible to stock) but got really loud when I wanted it to. It is all about what you want. GMMG is the best sounding Cat-back out there but expect to pay 2x over a Flowmaster, Magnaflow or Hooker. I will be running a Hooker Cat-back on my car and an electric cut-out. IMO nothing is better since I have a really low (Hooker has one of the lowest sounding ones out there) and quite sound for daily use and a Cut-out for when I need power.

 

I guess so, but then again, who puts on a cat-back for horsepower gains? Yes, I realize it will give a slight power increase, but I changed my exhaust for SOUND reasons, and I'll leave the real POWER gains upto headers (eventually) . But for the sound, the Flowmaster is pure quality, and sounds like a V8 should IMO .

 

From what I've read so far, Loudmouth seems to be the way to go if you want less restriction and great sound? My friend has that set-up on his LT1 and I just everytime I hear it, I might look into that for my new car.

 

I just got the flowmaster 80's on my stock car, I think they sound great from the outside but like azz on the inside. How do you think it would sound with a pair of longtube headers?