Flowmaster cat back
TECH Senior Member
iTrader: (1)
Joined: Apr 2005
Posts: 8,807
Likes: 0
From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*
Originally Posted by nvrlast
Im so sick of hearing people saying that you "lose power" with flow master! I personaly think its BS and I'll tell you why. I know 3 F bodys that have it and there car responds to mods and dynos just like everyone elses. My car personaly dynod 311 hp and 327 ft lbs of torque. Thats with just an MTI clear lid and flowmaster cat back and Y pipe. My car went 13.01 at 108 MPH with the factory 245's with just the lid,coldair and flowmaster. I have a friend that has a comp cam dont remember the specs though, hooker headers and flowmaster and hes making 380 hp and went 12.4 on some drag radials. and I have a friend with a 383 stroker and hes making 420 hp and 448 ft lbs of torque. I know that if you had something like the SLP loud mouth with that glass pack muffler that sounds like crap its gonna obviously flow better but I think thats the only one that you would see a power difference. I think that everyone can agree that any cat back you go with will give you 8-10 hp and thats it. You should deffinatley just buy a cat back for sound and thats it. My car runs strong and so does everyone elses that has flow master that I know. So Id say if you like the sound dont swap it. If you want power do a cut out because that will give you more power then having any kind of muffler on there.
yup---no more than 10 or so horse from ANY CAT-BACK....there is NOT huge power to be made from a 'MAGIC' muffler...... 
[10 hp is 10hp..i know...but i like sound also..very mucho] Last edited by NHRAMAN; Sep 4, 2006 at 05:43 PM.
TECH Senior Member
iTrader: (1)
Joined: Apr 2005
Posts: 8,807
Likes: 0
From: Vancouver,[KITSILANO].B.C. Canada *WestCoast*
Originally Posted by wannafbody
swap out the FM80 for a Spintech muffler-flows good and sounds great
Thread Starter
12 Second Club
Joined: Feb 2006
Posts: 993
Likes: 3
From: Waukesha,WI
I don't believe it is but i suppose i'll just leave the muffler and wait until i get my long tubes and y-pipe and add cut outs and i'll just buy different tips for the flowmaster cat back i like the way it sounds i would also like it to be louder with out rasp
i have the same thing with the flowmaster muffler.. i got long tubes n ory and i like the sound but i might be switching to a SLP loud mouth.... getting it for nuttin might change it to see if i does produce any more power
I put the american thunder catback on my 99 when I first got it, 
mistake. I also purchased the slp y-pipe that replaces the factory one. Another mistake. I felt no difference in power when these were on my car. It also had an annoying popping sound under deceleration, so it was not a good setup to me. However, I have since became more informed on the subject and have switched my setup to long tube headers, true duals with 1 chamber flows. When I went this route, I felt a noticable difference in power. If you are just going to swap mufflers, put a hooker aerochamber muffler on it like what comes in the hooker catback. I have seen several dynos posted on this site where only 3-5 hp was lost between the muffler and an open cutout.
mistake. I also purchased the slp y-pipe that replaces the factory one. Another mistake. I felt no difference in power when these were on my car. It also had an annoying popping sound under deceleration, so it was not a good setup to me. However, I have since became more informed on the subject and have switched my setup to long tube headers, true duals with 1 chamber flows. When I went this route, I felt a noticable difference in power. If you are just going to swap mufflers, put a hooker aerochamber muffler on it like what comes in the hooker catback. I have seen several dynos posted on this site where only 3-5 hp was lost between the muffler and an open cutout. LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
well i got my lt's and ORY and now i am in desperate need of a new muffler, i used to like the way my flowmaster sounded, not so much anymore. . .
magnaflow or hooker with lt's/ory !
if you like the way the flowmaster catback sounds with lt's and an ory you are one sick individual, and should be rushed to the emergency room immediatly.
magnaflow or hooker with lt's/ory !
if you like the way the flowmaster catback sounds with lt's and an ory you are one sick individual, and should be rushed to the emergency room immediatly.
TECH Addict
Joined: Jun 2005
Posts: 2,660
Likes: 14
From: England
Originally Posted by LILWS6
I bought my car used and the previous owner had installed a flowmaster cat back on it. i'm hearing horrible stories about how bad they flow. is it the cat back its self or the muffler? if its just the muffler who makes a better flowing muffler that i can just bolt up so i don't have to buy a new exhaust. i love the corsa look but i think i'll just put on tips. so i need a better flowing muffler and i don't care how loud it is just want flow and bolt right up.
)Anyhow, yes the Flowmaster is a restriction HOWEVER it's not as bad as people claim. For starters the 80 Series muffler is better than stock and uses larger tubing for the rest of the catback. So it IS an improvement.
Also at the level of mods you are at, you will see somewhere in the region of BUGGER ALL gain in HP by swapping to abother setup.
You can not unbolt the muffler, you'll find its welded onto the inlet and outlet pipes. It has one in and two out.
This means to replace it, you need an alternative muffler with 1 in 2 out and roughly the same shape and size else it will require fab work.
A cheaper option is just get an electric cutout or even another catback.
Personally there are like a hundred other mods which would benefit you much more than worrying about the exhaust. Do them first and then sort out the exhaust.
An no, even on a cammed setup you will not see gains in the region of 30HP. If your setup is capable of 400+rwhp then a cutout would probably buy you an extra 5-15rwhp at most (setup dependant).
